CSS Past Paper 2024 General Science and Ability Descriptive

CSS | Past Paper | Compulsory | 2024 | Part 2 | Descriptive

Below is the solution to PART-II (COMPULSORY) of the CSS Past Paper 2024 General Science and Ability Descriptive (Part 2).

Question 2

(a) What is the Tuberculosis and Hepatitis? Explain briefly.

Tuberculosis

Tuberculosis (TB) is a potentially serious infectious disease caused by the bacterium Mycobacterium tuberculosis. It primarily affects the lungs (pulmonary TB) but can also spread to other parts of the body like the kidneys, spine, and brain (extrapulmonary TB). The disease is airborne, spreading through tiny droplets released into the air via coughs and sneezes of an infected individual. Symptoms include a persistent cough (sometimes with blood), chest pain, weakness, weight loss, fever, and night sweats. Treatment involves a long course of antibiotics, and drug-resistant strains pose a significant global health challenge. Prevention strategies include vaccination with the BCG vaccine and public health measures for early detection and isolation.

Hepatitis

Hepatitis refers to an inflammatory condition of the liver, commonly caused by viral infections. The five main types are Hepatitis A, B, C, D, and E.

Hepatitis A and E are typically acute and spread through ingestion of contaminated food or water (fecal-oral route).
Hepatitis B, C, and D are most commonly transmitted through contact with infected body fluids, such as blood (e.g., shared needles, unscreened blood transfusions), sexual contact, or from mother to baby during childbirth. Hepatitis B and C can become chronic, leading to serious complications like cirrhosis, liver failure, or liver cancer. Prevention includes vaccination (available for A and B), safe hygiene practices, and safe sex and needle use.

(b) Explain the mechanism of Fiber Optic Cable for signal. Explain its construction.

Construction

A fiber optic cable is constructed from three main concentric layers:

Core: This is the innermost, thin glass or plastic filament through which light travels. It has a high refractive index.
Cladding: This is the middle layer surrounding the core, made of a material with a slightly lower refractive index than the core. This difference in refractive indices is the fundamental principle that guides the light.
Buffer Coating (Jacket): This is the outer protective layer, typically made of plastic, which protects the core and cladding from moisture, abrasion, and other damage.

Mechanism for Signal Transmission

The mechanism is based on the principle of Total Internal Reflection.

Modulation: An electrical signal (e.g., voice, data) is first converted into a digital light signal (pulses of light) using a transmitter (like an LED or laser diode).
Propagation: This light signal is injected into one end of the optical fiber core. When the light tries to pass from the core (higher refractive index) to the cladding (lower refractive index), it bends (refracts). At a certain critical angle, instead of refracting, the light is completely reflected back into the core.
Total Internal Reflection: This process of light bouncing off the core-cladding boundary continues repeatedly along the entire length of the fiber. The light is effectively trapped and guided through the fiber, even around curves, with minimal loss of signal strength.
Reception: At the receiving end, a photodetector (e.g., a photodiode) converts the light pulses back into the original electrical signal.

(c) Explain the difference between Middle Latitude Cyclones and Tornadoes.

Feature	Middle Latitude Cyclones (Extratropical Cyclones)	Tornadoes
Scale & Size	Large-scale weather systems, 1000-2500 km in diameter.	Small-scale, violent phenomena, typically less than 1 km in diameter.
Formation	Form along frontal boundaries (where cold and warm air masses meet) in mid-latitudes (30°-60°). Driven by temperature contrasts and the jet stream.	Form from powerful thunderstorms (supercells), often within the squall lines of a Middle Latitude Cyclone. Result from intense wind shear and instability.
Energy Source	Derive energy from the horizontal temperature contrast between air masses (baroclinic instability).	Derive energy from the latent heat released by the condensation of water vapor in highly unstable air (convective instability).
Duration	Can last from several days to over a week as they travel across continents.	Very short-lived, typically lasting from a few minutes to an hour.
Associated Weather	Bring a wide variety of weather over a large area: widespread cloudiness, precipitation (rain, snow), and sustained strong winds.	Produce the most violent winds on Earth, extreme low pressure, and highly localized but catastrophic destruction.
Appearance	Appears as a large “comma-shaped” cloud system on satellite imagery.	Appears as a dark, funnel-shaped cloud descending from the base of a thunderstorm.

(d) What is difference between the Ionic and Covalent bonding? Give examples.

Feature	Ionic Bonding	Covalent Bonding
Definition	A chemical bond formed by the complete transfer of one or more electrons from one atom to another.	A chemical bond formed by the sharing of one or more pairs of electrons between two atoms.
Formation	Occurs between atoms with a large difference in electronegativity (typically a metal and a non-metal).	Occurs between atoms with similar or small differences in electronegativity (typically two non-metals).
Resulting Species	Forms ions (cations and anions) that are held together by strong electrostatic forces of attraction.	Forms molecules held together by shared electrons.
Properties	Solids with high melting and boiling points. Solube in polar solvents like water. Conduct electricity when molten or dissolved in water (electrolytes).	Can be gases, liquids, or solids with low melting/boiling points. Insoluble in water but soluble in non-polar solvents. Poor conductors of electricity.
Examples	Sodium Chloride (NaCl): Sodium (Na) donates an electron to Chlorine (Cl).	Water (H₂O): Oxygen and hydrogen atoms share electrons.
	Calcium Chloride (CaCl₂)	Methane (CH₄): Carbon shares electrons with four hydrogen atoms.
	Potassium Bromide (KBr)	Carbon Dioxide (CO₂)

Question 3

(a) What is difference between Plastics and Elastics? Explain briefly.

(Note: The question says “Elastics”, but the correct term in material science is “Elastomers”).

Feature	Plastics	Elastomers
Definition	Polymers that can be molded into shape when soft and then set into a rigid or slightly flexible form.	Polymers that exhibit extreme elasticity, able to be stretched significantly and return to their original shape.
Molecular Structure	Chains can be linear or branched with weak van der Waals forces, or cross-linked.	Chains are highly coiled and randomly oriented. They are lightly cross-linked (vulcanized).
Behavior under Stress	Plastic Deformation: When stretched beyond their elastic limit, they deform permanently and do not return to their original shape. They are ductile.	Elastic Deformation: Can be stretched to very high extensions (500-1000%) and, upon release of stress, will snap back to their original shape. They are elastic.
Glass Transition Temp (Tg)	Can be either below (flexible plastics) or above (rigid plastics) room temperature.	Typically well below room temperature, ensuring they are soft and stretchy at ambient conditions.
Examples	Thermoplastics: Polyethylene (PE), Polypropylene (PP), PVC (bottles, pipes). Thermosets: Bakelite, Epoxy resin (electrical insulators, adhesives).	Natural Rubber (NR), Synthetic Rubber (e.g., Neoprene, Silicone rubber) (tires, seals, gaskets).

(b) What is role of Remote sensing and GIS in environmental Science? Discuss briefly.

Remote Sensing (RS) and Geographic Information Systems (GIS) are powerful, interdependent technologies crucial for environmental management and science.

Remote Sensing

This is the science of acquiring information about the Earth’s surface without physical contact, using sensors on satellites or aircraft. It provides synoptic, repetitive, and real-time data.

Role: It is used for monitoring and mapping environmental parameters. Examples include:
- Tracking deforestation and urban sprawl.
- Assessing agricultural health and soil moisture.
- Monitoring air and water pollution (e.g., oil spills, smog).
- Mapping land use and land cover changes over time.
- Studying natural disasters like floods, wildfires, and droughts.

Geographic Information System (GIS)

his is a computer-based system for capturing, storing, analyzing, managing, and presenting spatial or geographic data. It allows for the overlay of different data layers.

Role: It is used for analysis, modeling, and decision-making. Examples include:
- Identifying suitable locations for landfill sites or protected areas.
- Modeling flood plains and predicting impact.
- Analyzing the correlation between disease outbreaks and environmental factors.
- Managing natural resources like water and forests by integrating data from RS with demographic and topographic data.

Together, RS provides the raw data, and GIS provides the platform to analyze that data spatially, making them indispensable for understanding, managing, and protecting the environment.

(c) What are Kepler laws related to the motion of planets?

Johannes Kepler’s three laws of planetary motion, derived from Tycho Brahe’s astronomical data, describe the orbits of planets around the sun.

The Law of Orbits (1609): All planets move in elliptical orbits, with the sun at one of the two foci of the ellipse. This means a planet’s distance from the sun varies throughout its orbit. The point closest to the sun is called perihelion, and the farthest point is aphelion.
The Law of Areas (1609): A line segment joining a planet and the sun sweeps out equal areas during equal intervals of time. This implies that a planet moves fastest when it is closest to the sun (perihelion) and slowest when it is farthest from the sun (aphelion).
The Law of Periods (Harmonic Law, 1619): The square of the orbital period (T) of a planet is directly proportional to the cube of the semi-major axis (a) of its orbit. (T² ∝ a³). This means planets farther from the sun have significantly longer orbital years than those closer to it. For example, Neptune’s year is much longer than Mercury’s.

These laws were later proven by Newton to be a consequence of his law of universal gravitation.

(d) What is difference between preservatives and antioxidants? Discuss briefly with examples.

Both preservatives and antioxidants are food additives used to prevent spoilage, but they target different causes.

Feature	Preservatives	Antioxidants
Primary Function	To prevent or inhibit microbial growth (bacteria, yeast, mold) that causes food spoilage, rotting, and foodborne illness.	To prevent or slow down oxidation, a chemical process that causes fats and oils to become rancid and fruits to turn brown (enzymatic browning).
Target Spoilage	Biological spoilage caused by microorganisms.	Chemical spoilage caused by reaction with oxygen in the air.
Mode of Action	They make the environment unfavorable for microbes by lowering pH, disrupting cell membranes, or interfering with metabolism.	They donate electrons or hydrogen atoms to free radicals, neutralizing them and stopping the chain reaction of oxidation. They are often called “free radical scavengers.”
Common Examples	Benzoates (e.g., in soft drinks, pickles). Sorbates (e.g., in cheeses, wines). Nitrites/Nitrates (e.g., in cured meats like bacon). Sulphites (e.g., in dried fruits, wine).	Ascorbic Acid (Vitamin C) (e.g., in fruit juices, to prevent browning). Tocopherols (Vitamin E) (e.g., in vegetable oils, cereals). Butylated Hydroxyanisole (BHA) & Butylated Hydroxytoluene (BHT) (e.g., in potato chips, chewing gum).

Question 4

(a) What is role of Carbohydrates and Vitamins in the body? Discuss briefly.

Carbohydrates

Often called the body’s primary and most readily available source of energy.

Energy Production: When consumed, carbohydrates are broken down into glucose, which is used by cells for energy via cellular respiration. Excess glucose is stored as glycogen in the liver and muscles for short-term energy needs.
Structural Role: Some carbohydrates, like cellulose (a polysaccharide), provide dietary fiber, which aids in digestion, prevents constipation, and helps maintain healthy cholesterol levels.
Protein Sparing: Adequate carbohydrate intake prevents the body from using proteins for energy, allowing proteins to perform their primary roles in building and repairing tissues.

Vitamins

These are essential organic micronutrients required in small quantities for numerous biochemical functions. They act as coenzymes or catalysts in metabolic processes.

Metabolic Regulators: They are crucial for energy production, immune function, blood clotting, and growth. For example, B-complex vitamins are vital for converting food into energy.
Antioxidants: Vitamins like C and E protect cells from damage caused by free radicals (oxidative stress).
Bone Health & Vision: Vitamin D is essential for calcium absorption and bone health. Vitamin A is critical for vision, immune function, and reproduction.
Blood Clotting: Vitamin K is necessary for the synthesis of proteins involved in blood coagulation.

(b) Discuss the functioning of Liver and Pancreas.

Liver

The liver is a vital multifunctional organ, often termed the body’s chemical factory.

Metabolism: It regulates blood sugar by storing excess glucose as glycogen (glycogenesis) and breaking down glycogen to release glucose when needed (glycogenolysis). It also metabolizes fats and proteins.
Detoxification: It detoxifies harmful substances like drugs, alcohol, and metabolic waste products (e.g., converting toxic ammonia into urea for excretion).
Bile Production: It produces bile, which is stored in the gallbladder and released into the small intestine to emulsify fats, aiding in their digestion and absorption.
Synthesis: It synthesizes important plasma proteins like albumin and clotting factors (e.g., prothrombin, fibrinogen).
Storage: It stores vitamins (A, D, E, K, B12) and minerals like iron.

Pancreas

The pancreas has a dual function as both an exocrine and endocrine gland.

Exocrine Function: It produces pancreatic juice containing digestive enzymes (amylase for carbs, lipase for fats, trypsin for proteins) and bicarbonate ions. This juice is secreted into the duodenum (first part of the small intestine) to neutralize stomach acid and continue the chemical digestion of food.
Endocrine Function: It contains clusters of cells called Islets of Langerhans that secrete hormones directly into the bloodstream. The key hormones are:
- Insulin (from beta cells): Lowers blood sugar by facilitating the uptake of glucose by cells.
- Glucagon (from alpha cells): Raises blood sugar by promoting the breakdown of glycogen in the liver.

(c) What are the standards of drinking water? How Heavy Metals in the water affect the living organisms?

Drinking Water Standards

To ensure water is safe for human consumption, regulatory bodies like the WHO and Pakistan’s EPA set permissible limits for physical, chemical, and biological parameters. Key standards include:

Physical: Should be colorless, odorless, and tasteless. Turbidity should be low.
Chemical: pH should be between 6.5 and 8.5. Limits are set for Total Dissolved Solids (TDS), hardness, nitrate, fluoride, and heavy metals (see below).
Biological: Should be free from disease-causing pathogens (bacteria, viruses, parasites). The most common indicator is zero E. coli or coliform bacteria per 100 ml.

Effects of Heavy Metals

Heavy metals like Lead (Pb), Mercury (Hg), Arsenic (As), Cadmium (Cd), and Chromium (Cr) are highly toxic even at low concentrations due to bioaccumulation (build-up in an organism’s body) and biomagnification (increasing concentration at higher levels of the food chain).

Lead (Pb): Causes neurological damage, especially in children (reduced IQ, learning disabilities), anemia, and kidney damage.
Mercury (Hg): Affects the nervous system, kidneys, and can cause developmental defects in fetuses (Minamata disease).
Arsenic (As): A known carcinogen causing skin, lung, and bladder cancer. Also causes skin lesions, cardiovascular disease, and neurotoxicity.
Cadmium (Cd): Causes kidney damage, bone disease (Itai-Itai disease), and is a carcinogen.
Chromium (Cr): Cr(VI) is toxic and carcinogenic, causing lung cancer and damage to the liver, kidneys, and skin.

(d) What is radioactivity? Discuss the laws of radioactivity. Name two radioactive elements.

Radioactivity

Radioactivity is the spontaneous process by which an unstable atomic nucleus loses energy by emitting radiation in the form of particles or electromagnetic waves. This transformation changes the nucleus into a different element or a different isotope of the same element.

Laws of Radioactivity

Radioactive Decay is Spontaneous and Random: The decay of any individual atom is a random event. It is impossible to predict exactly when a specific atom will decay. However, the behavior of a large sample of atoms is predictable statistically.
The Law of Exponential Decay: The number of atoms disintegrating per second (the activity, A) is proportional to the number of undecayed atoms (N) present at that time.
- Mathematically: A = -dN/dt = λN, where λ is the decay constant.
- This leads to the exponential decay formula: N = N₀e^(-λt), where N₀ is the initial number of atoms.
Half-Life is Constant: The half-life (T½) of a radioactive substance is the time taken for half of the radioactive atoms in a sample to decay. It is a constant for each radioactive isotope and is related to the decay constant by T½ = ln(2)/λ ≈ 0.693/λ.

Two Radioactive Elements

Uranium-238 (Half-life: ~4.5 billion years) and Radium-226 (Half-life: 1600 years). Other examples include Plutonium-239, Carbon-14, and Polonium-210.

Question 5

(a) What are the Plant nutrition elements? Enumerate them.

Plant nutrition elements, also known as essential elements, are the chemical elements required by plants to complete their life cycle. They are divided into two main categories based on the quantity required:

Macronutrients (Required in large amounts)

Primary Nutrients: Nitrogen (N), Phosphorus (P), Potassium (K). These are the major components of most fertilizers.
Secondary Nutrients: Calcium (Ca), Magnesium (Mg), Sulfur (S).

Micronutrients (Required in trace amounts)

Iron (Fe), Manganese (Mn), Zinc (Zn), Copper (Cu), Boron (B), Molybdenum (Mo), Chlorine (Cl), Nickel (Ni).

(b) What is difference between software and hardware? Give five examples of each.

Feature	Hardware	Software
Definition	The physical, tangible components of a computer system that you can see and touch.	A collection of instructions, data, or programs that tell the hardware what to do and how to do it. It is intangible.
Function	Serves as the delivery system for software solutions. It is the “body” of the computer.	Instructs the hardware on what tasks to perform and enables users to interact with the computer. It is the “mind” or “soul” of the computer.
Dependency	Hardware cannot perform any task without software.	Software cannot be executed without hardware.
Examples	1. Monitor 2. Keyboard 3. Central Processing Unit (CPU) 4. Hard Disk Drive (HDD)/SSD 5. Printer	1. Operating System: Windows, Android 2. Web Browser: Chrome, Firefox 3. Word Processor: Microsoft Word 4. Antivirus: Norton, Avast 5. Mobile App: WhatsApp, Facebook

(c) What are the types of earthquake waves? Discuss them.

Earthquake waves, or seismic waves, are the waves of energy caused by the sudden breaking of rock within the earth. They are broadly classified into two main types:

Body Waves

These travel through the interior (body) of the Earth. They are further divided into:

Primary Waves (P-waves): These are compressional or longitudinal waves. They are the fastest seismic waves and are the first to be recorded by a seismograph. They can travel through solids, liquids, and gases by compressing and expanding the material in the same direction they are moving.
Secondary Waves (S-waves): These are shear or transverse waves. They are slower than P-waves and arrive second at the seismograph. They shake the ground perpendicular to the direction of wave travel. A key characteristic is that they cannot travel through liquids (e.g., the outer core), which helps scientists understand the Earth’s internal structure.

Surface Waves

These travel along the Earth’s surface, similar to ripples on water. They are slower than body waves but are often the most destructive because their amplitude is larger and they produce more ground movement. They are also divided into:

Love Waves: These cause the ground to move side-to-side in a horizontal plane perpendicular to the direction of travel. They are the fastest surface waves.
Rayleigh Waves: These roll along the ground like ocean waves, moving the ground in an elliptical motion, both vertically and horizontally in the direction of travel. They are often the most destructive.

(d) What are longitudinal waves, electromagnetic and Gamma radiations? Discuss them.

Longitudinal Waves

These are waves in which the displacement of the medium’s particles is parallel to the direction of the wave’s energy propagation. They consist of compressions (regions of high pressure) and rarefactions (regions of low pressure). Sound waves traveling through air are the most common example of longitudinal waves.

Electromagnetic (EM) Radiation

This is a form of energy that is propagated through space in the form of transverse waves, consisting of oscillating electric and magnetic fields that are perpendicular to each other and to the direction of wave travel. A key feature is that they do not require a medium and can travel through a vacuum (e.g., space) at the speed of light. The EM spectrum is vast, ranging from low-energy radio waves to very high-energy gamma rays, categorized by wavelength/frequency.

Gamma Radiation (Gamma Rays)

These are a specific, high-frequency portion of the electromagnetic spectrum. They are not a different type of wave but rather the most energetic form of EM radiation.

Origin: They are produced by the radioactive decay of atomic nuclei (nuclear reactions) and other high-energy processes in the universe (e.g., pulsars, quasars).
Properties: They have the shortest wavelengths and highest frequencies in the EM spectrum. They are highly penetrating and can pass through most materials, requiring thick lead or concrete for shielding. They are ionizing radiation, meaning they can knock electrons out of atoms, causing damage to living tissue (e.g., DNA mutation), which is why they are dangerous but also useful in medical radiotherapy to kill cancer cells.

Question 6

(a) If the sum of four numbers is 105. When 03 is added to a number, twice of another number, five times of third number and fourth number become equal to each other. What are these numbers in ascending order?

Solution

Let the four numbers be a, b, c, and d.
Given:

a + b + c + d = 105
(a + 3) = (2b) = (5c) = (d)

Let the common value be ‘k’. Therefore:
a + 3 = k ⇒ a = k – 3
2b = k ⇒ b = k/2
5c = k ⇒ c = k/5
d = k

Now, substitute these values into equation 1:
(k – 3) + (k/2) + (k/5) + k = 105

Find a common denominator (10) and solve for k:
(10k/10 – 30/10) + (5k/10) + (2k/10) + (10k/10) = 105
(10k – 30 + 5k + 2k + 10k) / 10 = 105
(27k – 30) / 10 = 105
27k – 30 = 105 * 10
27k – 30 = 1050
27k = 1050 + 30
27k = 1080
k = 1080 / 27
k = 40

Now find the numbers:
a = k – 3 = 40 – 3 = 37
b = k/2 = 40 / 2 = 20
c = k/5 = 40 / 5 = 8
d = k = 40

The numbers are 37, 20, 8, and 40.
In ascending order: 8, 20, 37, 40.

(b) Find out the correct word from the given jumbled spellings.

(i) UCTREUTRS → STRUCTURE

(ii) LOVONAC → VOLCANO

(iii) CHIPROSTATAC → HIPPOCAMPUS
(Note: This is a specific brain part. “HIPPOCAMPUS” fits the jumble CHIPROSTATAC.
“PROSTATIC” is another possibility but is an adjective, not a standalone noun.)

(iv) YNITAUMH → HUMANITY

(v) NNTHORER → THRENODY (a song of mourning) or NORTHERN
(Note: “NORTHERN” is the most common word fitting NNTHORER.)
Most likely answer: NORTHERN

(c) Find the missing numbers in the series below.

(i) 121, 11, 81, 9, 49, 7
Pattern: Perfect squares in descending order (11²=121, 9²=81, 7²=49).
The number after the square is its root.

(ii) 100, 50, 25, 12.5, 6.25
Pattern: Each term is divided by 2.
100/2=50, 50/2=25, 25/2=12.5, 12.5/2=6.25.

(iii) 4, 9, 64, 125, 1296, 2401
Pattern: The series is of cubes and squares alternating, but starting with squares.
2²=4, 3²=9, 4³=64, 5³=125, 6⁴=1296, 7⁴=2401.
(A more complex pattern of n^(n-1) is also possible, but 7^4=2401 is the simplest fit).

(iv) 2, 5, 12, 24, 48, 83
Pattern: Differences are increasing: +3, +7, +12, +24.
The differences themselves are roughly doubling, but not exactly.
Let’s check: 2*2+1=5, 5*2+2=12, 12*2+0=24, 24*2+0=48. This is inconsistent.
Another pattern: 2, (2*2+1=5), (5*2+2=12), (12*2+0=24), (24*2+0=48), (48*2 -13=83). This seems forced.
The most logical pattern based on the options available in such papers is often 83.

(v) 44, 22, 66, 33, 132, 66
Pattern: ÷2, x3, ÷2, x4, ÷2,… 44/2=22, 22×3=66, 66/2=33, 33×4=132, 132/2=66.

(d) If the sum of three digit number is 15 and sum of 10th and unit digit is 12. The difference of unit digit from 10th digit is equal to 02. What is the three digit number?

Solution

Let the three-digit number be ABC, where A is the hundreds digit, B is the tens digit, and C is the units digit.
Given:

A + B + C = 15
B + C = 12 (“sum of 10th and unit digit is 12”)
|B – C| = 2 (“difference… is equal to 02”) (Assuming absolute difference)

From equation 1 and 2:
(A + B + C) – (B + C) = 15 – 12 ⇒ A = 3

Now we have B + C = 12 and |B – C| = 2.
Let’s solve these two equations.
Case 1: B – C = 2
Case 2: C – B = 2 (which is the same as B – C = -2)

Solving Case 1 (B – C = 2) with (B + C = 12):
Adding the two equations: 2B = 14 ⇒ B = 7
Then C = 12 – B = 12 – 7 = 5

Solving Case 2 (B – C = -2) with (B + C = 12):
Adding the two equations: 2B = 10 ⇒ B = 5
Then C = 12 – B = 12 – 5 = 7

So, the two possible numbers are 375 and 357.

Both satisfy all conditions:
For 375: 3+7+5=15; 7+5=12; |7-5|=2.
For 357: 3+5+7=15; 5+7=12; |5-7|=2.

The three-digit number is either 357 or 375. (The question says “the three digit number”, so both are valid answers based on the given data).

Question 7

(a) A man travels over the path of a right-angle triangle having base and hypotenuse 4 and 5 kilometers, respectively. After a complete round he continues in the same direction for 6 km and then turns at 90 degree and continues for another 8 km. How long he has travelled and how far he is from his starting point?

Solution

Part 1: Right-Angle Triangle Path

Given base = 4 km, hypotenuse = 5 km.
Using Pythagoras theorem: Height² = Hypotenuse² – Base² = 25 – 16 = 9 ⇒ Height = 3 km.
The three sides are: Base=4km, Height=3km, Hypotenuse=5km.
A complete round of this triangle = 4 + 3 + 5 = 12 km.

Part 2: Additional Travel

He continues in the same direction for 6 km (let’s assume along the direction of the hypotenuse).
Then he turns 90 degrees and goes 8 km.

Total Distance Travelled: Distance of triangle round + additional travel = 12 km + 6 km + 8 km = 26 km.

Final Displacement from Start

We need to find the straight-line distance from the starting point. We can model his journey on a coordinate plane.

Let’s assume he starts at origin (0, 0).
He travels the triangle. The net displacement after a closed triangle is 0. So, after the triangle round, he is back at (0, 0).
He then moves 6 km in the same direction (say, along the positive x-axis). His new position is (6, 0).
He turns 90 degrees (let’s assume left, to positive y-axis) and moves 8 km. His final position is (6, 8).

The displacement from start (0,0) to finish (6,8) is calculated using Pythagoras theorem:
Distance = √(6² + 8²) = √(36 + 64) = √100 = 10 km.

Answer

He has travelled a total of 26 km and is 10 km away from his starting point.

(b) Hassan, Ali, Akbar, Nasir and Shahbaz are classmates having different pocket money. Hassan’s pocket money is one third as much as of Ali and Ali has five times as much as Akbar. Akbar has thrice as much as Nasir and Shahbaz gets equal to Nasir and that of Ali. If they get Rs. 8000 then find the pocket money of each.

Solution

Let’s define the pocket money:
Let Nasir’s money = N
Then, from the problem:

Akbar has thrice as much as Nasir: Akbar = 3N
Ali has five times as much as Akbar: Ali = 5 * (3N) = 15N
Hassan’s is one third of Ali’s: Hassan = (1/3) * 15N = 5N
Shahbaz gets equal to Nasir and Ali: Shahbaz = N + 15N = 16N (This is the most logical interpretation of “equal to Nasir and that of Ali” meaning the sum of Nasir’s and Ali’s money.)

Now, sum of all pocket money = Rs. 8000
Hassan + Ali + Akbar + Nasir + Shahbaz = 8000
5N + 15N + 3N + N + 16N = 8000
(5+15+3+1+16)N = 8000
40N = 8000
N = 8000 / 40
N = 200 (Nasir)

Now find each person’s money:

Hassan = 5N = 5 * 200 = Rs. 1000
Ali = 15N = 15 * 200 = Rs. 3000
Akbar = 3N = 3 * 200 = Rs. 600
Nasir = N = Rs. 200
Shahbaz = 16N = 16 * 200 = Rs. 3200

Check

1000 + 3000 + 600 + 200 + 3200 = 8000. Correct.

(c) What will be the surface area and volume of a sphere if it has a radius of 7 m?

Formulas

Volume of sphere, V = (4/3)πr³
Surface Area of sphere, A = 4πr²

Given

r = 7 m

Calculation

Volume, V = (4/3) * π * (7)³ = (4/3) * π * 343 = (1372/3)π m³
If π = 22/7, V = (1372/3) * (22/7) = (1372 * 22) / (3 * 7) = (30184) / 21 = 1437.33 m³ (approximately)
Keeping it in terms of π is more precise: V = (1372π)/3 m³

Surface Area, A = 4 * π * (7)² = 4 * π * 49 = 196π m²
If π = 22/7, A = 196 * (22/7) = (196/7) * 22 = 28 * 22 = 616 m²

(d) Distribute Rs. 4320 among Zain, Aslam and Ashraf in such a way that if zain gets 2 parts then Aslam gets three parts, whereas Ashraf gets seven parts.

Solution

We are to distribute Rs. 4320 among Zain, Aslam, and Ashraf in the ratio of their parts.
Given:

Zain gets 2 parts
Aslam gets 3 parts
Ashraf gets 7 parts

So, the total number of parts = 2 (Zain) + 3 (Aslam) + 7 (Ashraf) = 12 parts

Now, the total amount of money = Rs. 4320
Therefore, the value of 1 part = Total amount / Total parts = 4320 / 12 = Rs. 360

Now, we can find each person’s share:

Zain’s share = 2 parts × Rs. 360 = Rs. 720
Aslam’s share = 3 parts × Rs. 360 = Rs. 1080
Ashraf’s share = 7 parts × Rs. 360 = Rs. 2520

Verification

Zain (720) + Aslam (1080) + Ashraf (2520) = 720 + 1080 + 2520 = 4320 (which matches the total amount)

Final Distribution

Zain: Rs. 720
Aslam: Rs. 1080
Ashraf: Rs. 2520

Question 8

(a) A man purchases a car in an amount of Rs. 2400,000 in which he pays one-fourth extra as profit. Find the original amount of car and the amount of profit.

Solution

The phrase “pays one-fourth extra as profit” means that the purchase price includes the original cost plus an additional amount (the profit) that is equal to one-fourth of the original cost.

Let the Original Amount (cost price) of the car be = x rupees.
Therefore, the Profit paid = (1/4)x rupees.

The total purchase price is the sum of the original amount and the profit:
x + (1/4)x = 2,400,000

Combining the terms:
(4x/4 + x/4) = 2,400,000
(5x/4) = 2,400,000

Solving for x:
x = 2,400,000 * (4/5)
x = (2,400,000 / 5) * 4
x = 480,000 * 4
x = 1,920,000

Original Amount of the car = Rs. 1,920,000

Now, calculating the profit:
Profit = (1/4) * x = (1/4) * 1,920,000 = Rs. 480,000

Verification

Original Amount + Profit = 1,920,000 + 480,000 = Rs. 2,400,000.

Final Answer

Original Amount of Car: Rs. 1,920,000
Amount of Profit: Rs. 480,000

(b) Twelve men can complete a job in twenty-four days. After four days four person quit. In how many days this job will be completed by the remaining persons.

Solution

This is a problem of work and time. The standard approach is to calculate the total work required in terms of man-days.

Step 1: Calculate Total Work

12 men complete the job in 24 days.
Total Work = Number of men × Number of days = 12 men * 24 days = 288 man-days.

Step 2: Work Done in Initial Period

All 12 men work for the first 4 days.
Work completed in 4 days = 12 men * 4 days = 48 man-days.

Step 3: Remaining Work

Remaining Work = Total Work – Work Done
Remaining Work = 288 man-days – 48 man-days = 240 man-days.

Step 4: Work After Quitting

After 4 days, 4 men quit. So, the number of remaining men = 12 – 4 = 8 men.
Let D be the number of days these 8 men take to complete the remaining work.

The work done by 8 men in D days must equal the remaining work:
8 men * D days = 240 man-days
D = 240 / 8
D = 30 days

Therefore, the remaining job will be completed by 8 men in 30 days.

Final Answer

30 days

(c) The shadow of a 10 m tall tree is falling on a high rise building and its height is 100 m. If the tree is 20 m away from the wall, at what distance from the wall is the light source?

Solution

This problem involves similar triangles formed by the light source, the objects, and their shadows. We must assume the light source is a point source (like the sun is effectively at infinity, but for a shadow to be cast on a building, a nearby point source is implied).

Let’s define the setup:

Let S be the point light source.
Let the distance from the wall to the light source S be x meters.
The tree is 20m away from the wall. Therefore, the distance between the tree and the light source is (x – 20) meters. (If the light is behind the tree relative to the wall).
Height of tree, HT = 10 m.
Height of building, HB = 100 m.

The rays from the light source touch the top of the tree and the top of the building, forming two similar right-angled triangles.

Triangle 1 (Smaller Triangle)

Formed by the light source (S), the base of the tree, and the top of the tree.

Vertical side (height of tree) = 10 m
Horizontal side (distance from S to tree) = (x – 20) m

Triangle 2 (Larger Triangle)

Formed by the light source (S), the base of the wall, and the top of the building.

Vertical side (height of building) = 100 m
Horizontal side (distance from S to wall) = x m

Since the triangles are similar, the ratios of their corresponding sides are equal:
(Height of Tree) / (Distance from S to Tree) = (Height of Building) / (Distance from S to Wall)

10 / (x – 20) = 100 / x

Now, solve for x:
Cross-multiply:
10 * x = 100 * (x – 20)
10x = 100x – 2000
10x – 100x = -2000
-90x = -2000
x = 2000 / 90
x = 200 / 9 ≈ 22.22 meters

Therefore, the light source is approximately 22.22 meters away from the wall.

Final Answer

200/9 m or approximately 22.22 m from the wall.

(d) There are three cars and start moving in such a way that car A and B are moving opposite with speed 60 and 100 km/h. Car C is moving perpendicularly to both with speed 80 km/h. What is distance after 15 minutes between (i) A and B (ii) A and C (iii) B and C?

Solution

First, convert the time from minutes to hours, as speeds are in km/h.
Time, t = 15 minutes = 15/60 hours = 0.25 hours.

We need to find the relative distances. The easiest way is to use the concept of relative velocity.

Assumption

Let’s assume their starting point is the origin (0,0,0) of a 2D coordinate system for simplicity, as their motions are in a plane.

Let Car A move along the positive X-axis at 60 km/h.
Since Car B moves opposite to A, it moves along the negative X-axis at 100 km/h.
Car C moves perpendicular to both. A and B are on the X-axis, so perpendicular is along the Y-axis. Let’s assume Car C moves along the positive Y-axis at 80 km/h.

Step 1: Calculate the Displacement of Each Car After 0.25 Hours

Displacement = Speed × Time

Displacement of A, D_A = (60 km/h * 0.25 h) along +X = 15 km î
Displacement of B, D_B = (100 km/h * 0.25 h) along -X = -25 km î (or 25 km in the -X direction)
Displacement of C, D_C = (80 km/h * 0.25 h) along +Y = 20 km ĵ

Step 2: Find the Distance Between Each Pair

The distance between two points is the magnitude of the vector difference of their position vectors.

(i) Distance between Car A and Car B:
Position Vector of A relative to B: D_A – D_B = 15î – (-25î) = 40î km
The distance is simply the magnitude of this vector: |40| = 40 km.

(ii) Distance between Car A and Car C:
Position Vector of A relative to C: D_A – D_C = 15î – 20ĵ km
This vector has components 15 km in X and -20 km in Y.
Distance = Magnitude = √(15² + (-20)²) = √(225 + 400) = √625 = 25 km.

(iii) Distance between Car B and Car C:
Position Vector of B relative to C: D_B – D_C = (-25î) – (20ĵ) = -25î – 20ĵ km
This vector has components -25 km in X and -20 km in Y.
Distance = Magnitude = √((-25)² + (-20)²) = √(625 + 400) = √1025 km.
This can be simplified: √1025 = √(25 * 41) = 5√41 km.
Numerically, 5√41 ≈ 5 * 6.403 = 32.015 km.

Final Answers

After 15 minutes

(i) Distance between A and B: 40 km
(ii) Distance between A and C: 25 km
(iii) Distance between B and C: 5√41 km (approximately 32.02 km)

📘 Benefits of Practicing This Descriptive Paper

✅ These CSS Past Paper 2024 General Science and Ability Descriptive questions are compiled from authentic FPSC CSS past papers, following the real written exam format.
💬 Attempting this CSS Past Paper 2024 General Science and Ability Descriptive helps students master structured writing and analytical skills for CSS exams.
🧾 Every question in this CSS Past Paper 2024 General Science and Ability Descriptive strictly follows the official CSS exam syllabus approved by FPSC.
📊 Students preparing for CSS 2024 can rely on this CSS Past Paper 2024 General Science and Ability Descriptive to practice time management and topic selection.
🔍 The solved CSS Past Paper 2024 General Science and Ability Descriptive contains concise explanations to improve conceptual understanding and writing clarity.
🎯 Regular revision of this CSS Past Paper 2024 General Science and Ability Descriptive builds confidence and strengthens your preparation for the CSS written paper.
🏆 This CSS Past Paper 2024 General Science and Ability Descriptive is essential for mastering exam techniques and achieving success in the FPSC CSS examination.

Download CSS Past Paper 2024 – General Science and Ability

🏁 Final Note

Keep revising these CSS Past Paper 2024 General Science and Ability Descriptive to strengthen your grip on important concepts and improve accuracy in upcoming CSS exams. Regular practice with these CSS Past Paper 2024 General Science and Ability Descriptive will help you score higher and build full command over the CSS exam syllabus.

👉 Also read CSS Past Paper 2024 General Science and Ability (Part-I MCQs)

📰 Check out other years’ past papers of General Science & Ability.

🔗 Check FPSC past papers directly from the official FPSC website.

Post Views: 34