CSS 2024 General Science and Ability - solved subjective questions

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

Tuberculosis

Tuberculosis, or TB, is an infectious disease caused mainly by the bacterium Mycobacterium tuberculosis. It usually affects the lungs, although it may also involve lymph nodes, bones, kidneys, the brain and other organs. Pulmonary TB spreads through airborne droplets released when a person with active disease coughs, sneezes or speaks.

TB infection and TB disease are not the same. A person with TB infection carries the bacteria but has no symptoms and does not transmit the disease. In active TB disease, the bacteria multiply and may cause a persistent cough, chest pain, fever, night sweats, fatigue, weight loss and sometimes blood in the sputum. Diagnosis commonly combines clinical assessment, chest imaging and laboratory testing of sputum.

TB is preventable and curable. The BCG vaccine gives children useful protection against severe forms such as TB meningitis, but it does not reliably prevent all pulmonary infection. Active drug-susceptible TB is treated with a prescribed combination of antibiotics for several months. Completing the full regimen is essential because irregular treatment encourages drug resistance.

Hepatitis

Hepatitis means inflammation of the liver. It may result from viruses, alcohol, certain medicines, toxins, autoimmune disease or metabolic disorders. The principal viral forms are hepatitis A, B, C, D and E. Hepatitis A and E usually spread through contaminated food or water and are commonly acute. Hepatitis B, C and D are primarily blood-borne; B and C may become chronic and cause cirrhosis or liver cancer.

Symptoms may include fatigue, nausea, abdominal discomfort, dark urine, pale stools and jaundice, although many infections initially produce no obvious symptoms. Prevention depends on the type. Safe vaccines are widely used against hepatitis A and B, and hepatitis B vaccination also prevents hepatitis D because D requires hepatitis B infection. There is no vaccine for hepatitis C. Safe water, screened blood, sterile needles and infection-control practices reduce transmission. Treatment ranges from supportive care for many acute cases to antiviral therapy for chronic hepatitis B or curative direct-acting antivirals for most hepatitis C infections.

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

An optical-fibre cable carries information as pulses of light rather than as electric current. Its central core is a very clear strand of glass or plastic. The core is surrounded by cladding whose refractive index is slightly lower. A protective buffer coating, strengthening material and outer jacket guard the delicate fibre against moisture, bending and mechanical damage.

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

A middle-latitude cyclone, also called an extratropical cyclone, is a large low-pressure weather system that develops mainly between about 30° and 60° latitude. It forms where contrasting warm and cold air masses meet along fronts. A tornado is a much smaller, violently rotating column of air extending from a thunderstorm cloud to the ground.

• Formation: A middle-latitude cyclone draws energy from horizontal temperature contrasts and develops warm and cold fronts. A tornado usually develops within a severe thunderstorm when instability, moisture and vertical wind shear produce a rotating updraft.
• Scale: A cyclone may extend over hundreds or more than a thousand kilometres and influence several regions. A tornado is normally tens to hundreds of metres wide, although exceptional tornadoes can be wider.
• Duration: A cyclone commonly persists for several days. Most tornadoes last minutes, though some remain on the ground much longer.
• Weather: A cyclone brings widespread cloud, changing winds and prolonged rain or snow. A tornado produces a narrow path of extremely intense winds and concentrated damage.
• Observation: Cyclones are tracked through pressure maps, satellites and weather models. Tornado intensity is assessed with the Enhanced Fujita scale from observed damage. The Saffir-Simpson scale applies to hurricanes, not middle-latitude cyclones.

Both systems rotate around low pressure, counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere at cyclone scale. Tornado rotation is strongly shaped by its parent storm and local wind shear.

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

Chemical bonds hold atoms together by involving their valence electrons. In ionic bonding, one atom transfers one or more electrons to another. The transfer creates positively charged cations and negatively charged anions, which remain together because opposite charges attract. Ionic bonding is common between a metal and a non-metal. Sodium chloride is formed when sodium transfers an electron to chlorine, producing Na+ and Cl- ions. Magnesium oxide, MgO, is another example.

In covalent bonding, atoms share one or more pairs of electrons. It is common between non-metals whose attraction for electrons is similar enough to favour sharing rather than complete transfer. Two hydrogen atoms share electrons with oxygen in water, H2O. Methane, CH4, oxygen, O2, and carbon dioxide, CO2, also contain covalent bonds.

The resulting properties differ. Ionic compounds usually form crystalline solids with relatively high melting points. They conduct electricity when molten or dissolved in water because their ions can move, but they generally do not conduct as solids. Covalent substances may be gases, liquids or solids and often have lower melting points, although giant covalent structures such as diamond are major exceptions. Most simple covalent substances do not conduct electricity because they lack mobile charged particles.

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

The printed term “Elastics” is not the usual technical category. In polymer science, the intended comparison is between plastics and elastomers. Both consist of long-chain polymers, but their molecular structures and mechanical behaviour differ.

Plastics can be moulded into a desired shape and normally retain that shape after the applied force is removed. Their polymer chains have limited freedom to move. Thermoplastics such as polyethylene and PVC soften on heating and can be remoulded. Thermosetting plastics such as Bakelite form dense cross-links during curing and cannot be reshaped by reheating. Plastics are used for containers, pipes, electrical insulation, furniture and machine parts.

Elastomers can be stretched, compressed or bent considerably and then recover most of their original shape. Their chains are flexible and coiled, with a small number of cross-links that prevent permanent sliding while allowing temporary extension. Natural rubber, silicone rubber and neoprene are common examples. They are used in tyres, seals, gloves, hoses and shock absorbers.

Thus, the central distinction is not simply that one material is hard and the other is soft. Plastics are designed mainly for shape retention and mouldability, whereas elastomers are designed for large reversible deformation and resilience.

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

Remote sensing obtains information about the Earth without direct contact, usually through sensors on satellites, aircraft or drones. These sensors record reflected or emitted energy in visible, infrared, microwave and other bands. Geographic Information Systems, or GIS, store, combine, analyse and display data linked to location.

Remote sensing provides repeated coverage of large or inaccessible areas. It can identify changes in forests, crops, glaciers, wetlands, coastlines and urban land. Thermal data help map heat islands and wildfires, while multispectral observations can indicate vegetation stress, sediment, algal blooms or changes in surface water. Radar can acquire information through clouds and can help map floods or ground deformation.

GIS gives these observations analytical meaning. A researcher can overlay satellite imagery with elevation, rainfall, soil, population, roads and administrative boundaries. Spatial analysis then reveals patterns, exposure and change through time. It supports watershed management, habitat protection, pollution mapping, environmental-impact assessment and disaster planning.

The two tools are strongest when integrated. Remote sensing supplies timely observations; GIS connects them with field measurements and human information. Ground verification remains important because a remotely sensed signal may have more than one interpretation.

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

Johannes Kepler formulated three laws that describe planetary motion around the Sun.

1. Law of orbits: Every planet moves in an elliptical orbit with the Sun at one focus. The Sun is therefore not necessarily at the geometrical centre of the orbit. A planet’s distance from the Sun changes between perihelion, its nearest point, and aphelion, its farthest point.
2. Law of areas: A line joining a planet to the Sun sweeps out equal areas in equal intervals of time. To sweep the same area, the planet moves faster when it is near the Sun and more slowly when it is farther away. Its orbital speed is therefore not constant.
3. Law of periods: The square of a planet’s orbital period is proportional to the cube of the semi-major axis of its orbit: T² ∝ a³. For bodies orbiting the same central mass, T²/a³ is constant. Planets with larger orbits consequently require much more time to complete one revolution.

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

Preservatives are substances or processes used to delay food spoilage and extend safe shelf life. The category includes antimicrobial agents that inhibit bacteria, yeasts or moulds, as well as substances that slow chemical or enzymatic deterioration. Salt, sugar, vinegar, sodium benzoate, potassium sorbate and nitrites are familiar examples. Their suitability and permitted concentration depend on the food and applicable safety rules.

Antioxidants specifically slow oxidation. Oxidation can make fats rancid, destroy sensitive vitamins, alter colour and produce undesirable flavours. Antioxidants work by donating electrons or hydrogen, binding metal catalysts, removing oxygen or interrupting free-radical chain reactions. Ascorbic acid, tocopherols, rosemary extract, butylated hydroxyanisole and butylated hydroxytoluene are examples.

The categories overlap. An antioxidant used to delay oxidative spoilage is functioning as a preservative, but not every preservative is an antioxidant. Sodium benzoate mainly restrains microbial growth in acidic foods and is not used chiefly for antioxidant action. Tocopherol mainly protects oils against oxidation and therefore preserves quality through a different mechanism.

The clearest distinction is purpose and mechanism: “preservative” is the broader functional category, while “antioxidant” identifies substances that preserve by controlling oxidation. Neither category makes poor handling safe; hygiene, temperature control and suitable packaging remain essential.

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

Carbohydrates

Carbohydrates are sugars, starches and fibre composed mainly of carbon, hydrogen and oxygen. Their primary role is to provide energy. Digested carbohydrate is converted largely into glucose, which cells use to produce ATP. The brain and red blood cells rely heavily on glucose under ordinary conditions. Excess glucose can be stored as glycogen in the liver and muscles for later use; prolonged excess may be converted into fat.

Carbohydrates also spare protein from being used as fuel and help normal fat metabolism. Dietary fibre is not digested like starch, but it supports bowel movement, helps regulate blood glucose, contributes to satiety and provides substrate for beneficial gut microbes. Whole grains, pulses, fruit and vegetables provide carbohydrate together with fibre and micronutrients.

Vitamins

Vitamins are organic micronutrients needed in small quantities for normal metabolism, growth and maintenance. They do not supply energy directly. Many act as coenzymes: B vitamins assist energy metabolism, vitamin C supports collagen synthesis and antioxidant defence, and folate is essential for DNA formation. Fat-soluble vitamins have specialised roles: vitamin A supports vision and epithelial tissues, D regulates calcium and bone health, E protects cell membranes, and K is required for normal blood clotting.

Deficiency causes characteristic disorders, but excessive supplementation may also be harmful, particularly for fat-soluble vitamins that can accumulate in the body.

(b) Discuss the functioning of Liver and Pancreas.

Liver

The liver is the body’s largest internal gland and a central processing organ. Blood from the digestive tract reaches it through the hepatic portal vein, allowing absorbed nutrients and many chemicals to be processed before entering general circulation. The liver regulates blood glucose by storing glucose as glycogen and releasing or producing glucose when needed. It converts amino acids, forms urea from toxic ammonia, synthesises cholesterol and packages lipids.

It also produces plasma proteins, including albumin and several clotting factors. Liver cells modify medicines, alcohol and metabolic wastes so they can be eliminated. Kupffer cells help remove microbes and damaged blood cells. The liver produces bile, which carries waste products such as bilirubin and helps the small intestine digest and absorb fats. It also stores glycogen, iron and several vitamins.

Pancreas

The pancreas has exocrine and endocrine functions. Its exocrine cells release digestive enzymes into the small intestine. Amylase digests carbohydrates, lipase digests fats, and proteases digest proteins. Bicarbonate-rich fluid neutralises acidic material arriving from the stomach, creating a suitable environment for intestinal enzymes.

Its endocrine islets release hormones into the blood. Beta cells secrete insulin, which lowers blood glucose by promoting uptake and storage. Alpha cells secrete glucagon, which raises blood glucose by stimulating the liver. Together, these functions make the pancreas essential for digestion and glucose control.

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

Safe drinking water is judged through several linked standards rather than appearance alone.

• Microbiological quality: Water intended for drinking should not contain faecal indicator organisms such as E. coli in a 100 mL sample. Microbial contamination can cause diarrhoea, cholera, typhoid and other infections.
• Physical acceptability: Turbidity, colour, taste and odour should remain acceptable. High turbidity can shield microorganisms and reduce the effectiveness of disinfection.
• Chemical quality: Salts, nutrients, pesticides and toxic elements must remain within health-based national limits. As examples of widely used WHO guideline values, arsenic should not exceed 0.01 mg/L and lead should not exceed 0.01 mg/L. Local regulators may adopt different or more stringent standards.
• Radiological quality: Natural or artificial radionuclides should remain below screening and guidance levels established by the competent authority.

Heavy metals are persistent and cannot be destroyed biologically. Lead damages the nervous system, especially in children, and can impair learning, blood formation and kidney function. Arsenic exposure is associated with skin lesions, cardiovascular effects and increased cancer risk. Mercury can damage the brain and kidneys; methylmercury also biomagnifies in aquatic food chains. Cadmium accumulates in the kidneys and can weaken bones.

Plants and aquatic organisms may absorb these elements from contaminated water or sediment. Bioaccumulation in individuals and biomagnification through food webs can then expose fish, wildlife and humans even when the water concentration appears modest.

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

Radioactivity is the spontaneous transformation of an unstable atomic nucleus into a more stable state with the emission of particles or electromagnetic energy. The common emissions are alpha particles, beta particles and gamma rays. Individual nuclear decays are random, but a large sample follows precise statistical laws.

1. Exponential decay law: The number of undecayed nuclei decreases at a rate proportional to the number still present. If N₀ is the initial number, then N = N₀ exp(-λt), where λ is the decay constant.
2. Activity law: Activity is the number of decays per unit time and is given by A = λN. Its SI unit is the becquerel, equal to one decay per second.
3. Half-life relation: Half-life is the time required for half the original radioactive nuclei to decay. It is constant for a given radionuclide and is related to the decay constant by t½ = 0.693/λ.
4. Independence from ordinary conditions: Nuclear decay is generally unaffected by temperature, pressure, chemical combination or external physical state because it occurs within the nucleus.

Examples of naturally radioactive elements include uranium and radium. Uranium-238 undergoes a series of decays that eventually forms stable lead, while radium-226 decays principally by alpha emission to radon-222. Radioactivity is used in medicine, industry, research and age determination, but uncontrolled exposure can damage living tissue.

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

An element is considered essential to a plant when the plant cannot complete its life cycle without it, its function cannot be fully replaced by another element, and it participates directly in plant metabolism or structure. The modern standard list contains 17 essential elements.

Plants obtain three non-mineral elements mainly from air and water:

1. Carbon, C
2. Hydrogen, H
3. Oxygen, O

They require the following mineral macronutrients in comparatively large quantities:

1. Nitrogen, N
2. Phosphorus, P
3. Potassium, K
4. Calcium, Ca
5. Magnesium, Mg
6. Sulfur, S

They require these micronutrients in much smaller amounts:

1. Iron, Fe
2. Manganese, Mn
3. Boron, B
4. Zinc, Zn
5. Copper, Cu
6. Molybdenum, Mo
7. Chlorine, Cl
8. Nickel, Ni

Quantity does not indicate importance. A micronutrient is just as essential, but the plant needs less of it. Nitrogen is central to amino acids and chlorophyll; phosphorus contributes to ATP and nucleic acids; potassium regulates enzymes and water balance. Magnesium lies at the centre of chlorophyll, while iron supports electron transfer. Nickel is included because it activates urease, an enzyme needed for normal nitrogen metabolism. Deficiency or excess of any nutrient can restrict plant growth.

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

Hardware consists of the physical, tangible components of a computer system. These parts perform input, processing, storage, communication and output operations. Hardware can be seen and handled, although many components are housed inside the computer. It is manufactured from electronic, magnetic and mechanical materials and is subject to physical wear or damage.

Five examples of hardware are:

1. Central processing unit
2. Random-access memory
3. Solid-state drive or hard disk
4. Keyboard
5. Monitor

Software is the organised set of programs, instructions and related data that tells hardware what operations to perform. It is intangible. System software manages the computer and provides a platform, while application software helps the user perform particular tasks. Software does not wear out physically, but it may contain errors, become incompatible or require security updates.

Five examples of software are:

1. Microsoft Windows
2. Linux
3. Microsoft Word
4. Google Chrome
5. Adobe Photoshop

Hardware and software are interdependent. A word processor cannot operate without a processor, memory, storage and display. The same hardware becomes useful for different tasks when it runs different software. Firmware occupies an intermediate practical position: it is software stored in non-volatile memory that directly controls hardware devices.

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

An earthquake releases stored elastic energy from its focus as seismic waves. These are divided into body waves, which travel through the Earth, and surface waves, which move along or near its surface.

Body waves

1. Primary or P waves: These are compressional, longitudinal waves. Particles vibrate parallel to the direction of travel, producing alternate compression and expansion. P waves are the fastest seismic waves, arrive first at a station, and travel through solids, liquids and gases.
2. Secondary or S waves: These are shear, transverse waves. Particles move perpendicular to the direction of propagation. S waves are slower than P waves and travel only through solids because fluids cannot support sustained shear stress. Their absence through the Earth’s outer core helped demonstrate that the outer core is liquid.

Surface waves

1. Love waves: These move the ground horizontally from side to side, perpendicular to their direction of travel, with little vertical movement. They can cause severe damage to foundations.
2. Rayleigh waves: These produce a rolling, elliptical motion with both vertical and horizontal components, rather like waves on water. They are generally slower than Love waves but can persist for long periods.

Surface waves usually have larger amplitudes and cause much of the damage near the surface. Seismologists use the different arrival times and paths of these waves to locate earthquakes and study the Earth’s interior.

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

Longitudinal waves

In a longitudinal wave, particles of the medium vibrate parallel to the direction in which the wave travels. The motion produces alternating compressions, where particles are close together, and rarefactions, where they are farther apart. Longitudinal mechanical waves require a material medium. Sound in air, ultrasound and seismic P waves are examples. The particles oscillate locally; they do not travel with the disturbance from source to receiver.

Electromagnetic radiation

Electromagnetic radiation consists of coupled oscillating electric and magnetic fields. The two fields are perpendicular to each other and to the direction of propagation, so electromagnetic waves are transverse. They do not require a material medium and travel through a vacuum at the speed of light. The electromagnetic spectrum includes radio waves, microwaves, infrared, visible light, ultraviolet, X-rays and gamma rays. All have the same basic nature but differ in frequency, wavelength and photon energy.

Gamma radiation

Gamma radiation is the highest-frequency, shortest-wavelength region of the electromagnetic spectrum. Gamma photons are commonly emitted when an excited atomic nucleus loses energy during radioactive decay or nuclear reactions. They have no mass and no electric charge. Their strong penetrating ability makes dense shielding such as lead or thick concrete necessary. Gamma rays are used in cancer radiotherapy, sterilisation, industrial inspection and nuclear medicine, but ionisation from excessive exposure can damage DNA and tissue.

The key relationship is that gamma radiation is not separate from electromagnetic radiation. It is one particularly energetic form of it.

(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?

Let the four numbers be A, B, C and D. The conditions give:

A + B + C + D = 105

and

A + 3 = 2B = 5C = D

Let their common value be k. Then:

• A = k - 3
• B = k/2
• C = k/5
• D = k

Substitute these expressions into the sum:

(k - 3) + k/2 + k/5 + k = 105

Multiply throughout by 10:

10k - 30 + 5k + 2k + 10k = 1050

27k = 1080

k = 40

Therefore:

• A = 40 - 3 = 37
• B = 40/2 = 20
• C = 40/5 = 8
• D = 40

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

1. UCTREUTRS = STRUCTURE
2. LOVONAC = VOLCANO
3. CIHPROSTATAC = CATASTROPHIC
4. YNTIAUMH = HUMANITY
5. NNTHORER = NORTHERN

Each answer uses every supplied letter once. For example, CIHPROSTATAC rearranges into CATASTROPHIC, while NNTHORER rearranges into NORTHERN.

(c) Find the missing numbers in the series below

(i) 121, 11, 81, 9, ?, 7

The terms occur in square-root pairs:

• 121 = 11²
• 81 = 9²
• 49 = 7²

(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?

The printed “10th digit” means the tens digit. Let H, T and U represent the hundreds, tens and units digits.

The conditions are:

H + T + U = 15

T + U = 12

T - U = 2

Add the last two equations:

2T = 14

T = 7

Then:

U = 12 - 7 = 5

and:

H = 15 - 7 - 5 = 3

Place the digits in their stated positions: H = 3, T = 7 and U = 5.

(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?

(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.

The last relationship is awkwardly printed. The coherent intended reading is:

Shahbaz = Nasir + Ali

Let Nasir receive x.

• Nasir = x
• Akbar = 3x
• Ali = 5(3x) = 15x
• Hassan = (1/3)(15x) = 5x
• Shahbaz = x + 15x = 16x

Their total is Rs. 8,000:

x + 3x + 15x + 5x + 16x = 8000

40x = 8000

x = 200

Therefore:

• Nasir = Rs. 200
• Akbar = Rs. 600
• Hassan = Rs. 1,000
• Ali = Rs. 3,000
• Shahbaz = Rs. 3,200

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

Given radius:

r = 7 m

Using π = 22/7, the surface area is:

Surface area = 4πr²

= 4 × 22/7 × 7²

= 616 m²

The volume is:

Volume = (4/3)πr³

= 4/3 × 22/7 × 7³

= 4312/3 m³

= 1,437 1/3 m³ ≈ 1,437.33 m³

(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.

The required ratio is:

Zain : Aslam : Ashraf = 2 : 3 : 7

Total parts:

2 + 3 + 7 = 12

Value of one part:

Rs. 4,320 ÷ 12 = Rs. 360

Therefore:

• Zain = 2 × 360 = Rs. 720
• Aslam = 3 × 360 = Rs. 1,080
• Ashraf = 7 × 360 = Rs. 2,520

(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.

Interpret the printed amount Rs. 2400,000 as Rs. 2,400,000.

Let the original price be x. The profit is one-fourth of the original price:

Profit = x/4

The total price paid is:

x + x/4 = 2,400,000

5x/4 = 2,400,000

x = 2,400,000 × 4/5

x = Rs. 1,920,000

Profit:

Rs. 2,400,000 - Rs. 1,920,000 = 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.

Total work in man-days:

12 × 24 = 288 man-days

Work completed during the first four days:

12 × 4 = 48 man-days

Remaining work:

288 - 48 = 240 man-days

After four men leave, eight men remain. The additional time they require is:

240 ÷ 8 = 30 days

The phrase “by the remaining persons” asks for the time required by those eight workers after the four have left. That answer is 30 additional days. If total elapsed time from the beginning is required, add the first four days:

4 + 30 = 34 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?

(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?