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BCS Written General Science & Tech study materials
BCS Written General Science & Tech study resources

BCS Written General Science & Tech practice questions

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Question 1General Science: Physics and Chemistry Fundamentals

Which SI base unit is used to express the amount of a substance?

  1. The ampere
  2. The mole Correct answer.
  3. The kelvin
  4. The candela

Explanation

The mole is the SI base unit for amount of substance, defined by a fixed number of elementary entities (the Avogadro constant). The other three units measure temperature, luminous intensity, and electric current respectively, so they cannot express quantity of substance.

Question 2General Science: Physics and Chemistry Fundamentals

A body moves at constant velocity. What is true of the net force acting on it?

  1. It increases steadily
  2. It equals its weight
  3. It is zero Correct answer.
  4. It points along the motion

Explanation

Newton's first law states that a body continues in uniform motion only when the resultant force is zero. Constant velocity means no change in speed or direction, hence no acceleration and no net force. Weight is balanced by the normal or other supporting force.

Question 3General Science: Physics and Chemistry Fundamentals

Which quantity is a scalar?

  1. Acceleration
  2. Momentum
  3. Displacement
  4. Speed Correct answer.

Explanation

A scalar has magnitude only, while a vector has both magnitude and direction. Speed depends only on how fast an object moves, whereas displacement, acceleration, and momentum all carry direction information.

Question 4General Science: Physics and Chemistry Fundamentals

A 2 kg object is pushed with a net force of 8 N. What is its acceleration?

  1. 16 m/s²
  2. 6 m/s²
  3. 0.25 m/s²
  4. 4 m/s² Correct answer.

Explanation

Newton's second law gives a = F/m, so dividing 8 N by 2 kg yields 4 m/s². The result has units of metres per second squared because newtons are kilogram-metres per second squared.

Question 5General Science: Physics and Chemistry Fundamentals

What happens to the pressure of a fixed mass of gas at constant volume when its absolute temperature is doubled?

  1. It stays the same
  2. It falls to one quarter
  3. It halves
  4. It doubles Correct answer.

Explanation

At constant volume, pressure is directly proportional to absolute temperature (Gay-Lussac's law). Doubling the kelvin temperature therefore doubles the pressure, because the molecules strike the walls more often and with greater average momentum.

Question 6General Science: Physics and Chemistry Fundamentals

Which particle in an atom carries no electric charge?

  1. The proton
  2. The electron
  3. The positron
  4. The neutron Correct answer.

Explanation

Neutrons are electrically neutral, which is why they do not contribute to the atomic charge number. Protons are positive, electrons are negative, and positrons are positively charged antielectrons.

Question 7General Science: Physics and Chemistry Fundamentals

In a neutral atom, which electrons are involved in forming chemical bonds?

  1. The innermost electrons
  2. The outermost electrons Correct answer.
  3. Only the neutrons
  4. Only the protons

Explanation

Bonding depends on the valence electrons in the outermost shell, because these are least tightly bound and can be shared or transferred. Inner-shell electrons are held too strongly to take part in ordinary chemical reactions.

Question 8General Science: Physics and Chemistry Fundamentals

Which of these substances is a compound rather than a mixture?

  1. Air
  2. Brass
  3. Water Correct answer.
  4. Salt water

Explanation

A compound contains two or more elements chemically combined in fixed proportions, as in water, where hydrogen and oxygen are bonded. Mixtures such as air, brass, and salt water contain components that are not chemically joined and can vary in proportion.

Question 9General Science: Physics and Chemistry Fundamentals

A car speeds up uniformly from rest to 20 m/s in 5 s. What is its acceleration?

  1. 0.25 m/s²
  2. 4 m/s² Correct answer.
  3. 25 m/s²
  4. 100 m/s²

Explanation

Uniform acceleration equals the change in velocity divided by the time taken. The change is 20 m/s and the time is 5 s, giving 4 m/s². Multiplying instead of dividing gives 100, which is dimensionally wrong.

Question 10General Science: Physics and Chemistry Fundamentals

A block slides down a frictionless incline. Which statement about its acceleration is correct?

  1. It is zero because motion is steady
  2. It is g sin θ down the slope Correct answer.
  3. It equals g regardless of angle
  4. It is g cos θ down the slope

Explanation

The only force along the incline is the component of weight parallel to the surface, mg sin θ, so the acceleration is g sin θ. The perpendicular component mg cos θ is balanced by the normal reaction and produces no motion along the slope.

Question 11General Science: Physics and Chemistry Fundamentals

Two resistors of 6 Ω and 3 Ω are connected in parallel. What is the equivalent resistance?

  1. 2 Ω Correct answer.
  2. 18 Ω
  3. 9 Ω
  4. 4.5 Ω

Explanation

For parallel resistors, the reciprocals add: 1/R = 1/6 + 1/3 = 1/2, so R = 2 Ω. The equivalent resistance of a parallel network is always smaller than the smallest individual resistor.

Question 12General Science: Physics and Chemistry Fundamentals

A wave has a frequency of 50 Hz and a wavelength of 4 m. What is its speed?

  1. 12.5 m/s
  2. 200 m/s Correct answer.
  3. 54 m/s
  4. 0.08 m/s

Explanation

Wave speed equals frequency multiplied by wavelength, so 50 Hz × 4 m = 200 m/s. Frequency counts cycles per second and wavelength gives metres per cycle, so the product has units of metres per second.

Question 13General Science: Physics and Chemistry Fundamentals

An object is placed between a converging lens and its focal point. What kind of image is formed?

  1. Real, inverted, and the same size
  2. Real, inverted, and diminished
  3. Virtual, inverted, and diminished
  4. Virtual, upright, and magnified Correct answer.

Explanation

When the object lies inside the focal length of a converging lens, the refracted rays diverge and only their backward extensions meet, forming a virtual image. That image is upright and larger than the object, which is how a magnifying glass works.

Question 14General Science: Physics and Chemistry Fundamentals

Which statement correctly describes the difference between heat and temperature?

  1. Heat is measured in kelvin; temperature is measured in joules
  2. Heat and temperature are the same physical quantity
  3. Heat is energy in transit; temperature measures average kinetic energy Correct answer.
  4. Temperature is energy in transit; heat measures total energy

Explanation

Heat is energy transferred between bodies because of a temperature difference, whereas temperature is a measure of the average kinetic energy of the particles. A large cool body can contain more internal energy than a small hot one, so the two concepts are distinct.

Question 15General Science: Physics and Chemistry Fundamentals

In an exothermic reaction, what happens to energy?

  1. It is absorbed from the surroundings
  2. It is destroyed completely
  3. It is released to the surroundings Correct answer.
  4. It remains stored in the products

Explanation

Exothermic reactions release energy, usually as heat, because the products have lower enthalpy than the reactants. The energy is not destroyed but transferred to the surroundings, which warm up.

Question 16General Science: Physics and Chemistry Fundamentals

Which of these is a characteristic property of acids in aqueous solution?

  1. They feel slippery
  2. They turn blue litmus red Correct answer.
  3. They turn red litmus blue
  4. They react with ammonium salts to release ammonia

Explanation

Acids donate protons in water, giving an acidic pH that turns blue litmus red. The slippery feel and the release of ammonia from ammonium salts are typical of bases such as sodium hydroxide.

Question 17General Science: Physics and Chemistry Fundamentals

What is the pH of a solution with a hydrogen ion concentration of 1 × 10⁻³ mol/dm³?

  1. 10³
  2. 3 Correct answer.
  3. 11
  4. −3

Explanation

pH is the negative logarithm to base ten of the hydrogen ion concentration. Taking −log₁₀(10⁻³) gives 3, which is acidic. A pH of 11 would correspond to a hydrogen ion concentration of 10⁻¹¹ mol/dm³.

Question 18General Science: Physics and Chemistry Fundamentals

In the reaction 2H₂ + O₂ → 2H₂O, how many moles of water form from 4 moles of hydrogen with excess oxygen?

  1. 1 mole
  2. 8 moles
  3. 2 moles
  4. 4 moles Correct answer.

Explanation

The balanced equation shows that two moles of hydrogen produce two moles of water, a 1:1 ratio. Therefore 4 moles of hydrogen give 4 moles of water, provided oxygen is in excess.

Question 19General Science: Physics and Chemistry Fundamentals

Which type of radiation is deflected most strongly by a magnetic field?

  1. Gamma rays
  2. Beta particles Correct answer.
  3. Neutrons
  4. Alpha particles

Explanation

Beta particles are light, fast electrons with a single negative charge, so a given magnetic field bends them far more than the heavy, doubly charged alpha particles. Gamma rays and neutrons carry no charge and are undeflected.

Question 20General Science: Physics and Chemistry Fundamentals

An electric kettle rated 2000 W is used for 3 minutes. How much energy does it transfer?

  1. 600 kJ
  2. 36 kJ
  3. 360 kJ Correct answer.
  4. 6 kJ

Explanation

Energy equals power multiplied by time, and 3 minutes is 180 seconds. Multiplying 2000 W by 180 s gives 360 000 J, or 360 kJ. Forgetting to convert minutes to seconds gives an answer a factor of 60 too small.

Question 21General Science: Physics and Chemistry Fundamentals

A gas expands and does 300 J of work while absorbing 500 J of heat. What is the change in its internal energy?

  1. −200 J
  2. −800 J
  3. +800 J
  4. +200 J Correct answer.

Explanation

The first law of thermodynamics gives ΔU = Q − W, where Q is heat absorbed and W is work done by the gas. Substituting 500 J − 300 J yields +200 J, so the internal energy rises.

Question 22General Science: Physics and Chemistry Fundamentals

Two charges are separated by a distance r. If the distance is doubled while the charges stay the same, the electrostatic force becomes

  1. four times its original value
  2. one quarter of its original value Correct answer.
  3. twice its original value
  4. one half of its original value

Explanation

Coulomb's law states that the force is inversely proportional to the square of the separation. Doubling r multiplies the force by 1/2², giving one quarter of the original magnitude.

Question 23General Science: Physics and Chemistry Fundamentals

A 2 kg block moving at 3 m/s collides with and sticks to a stationary 1 kg block. What is their common velocity immediately after the collision?

  1. 3 m/s
  2. 1.5 m/s
  3. 4.5 m/s
  4. 2 m/s Correct answer.

Explanation

Momentum is conserved in a perfectly inelastic collision: (2 kg)(3 m/s) = (3 kg)v, so v = 2 m/s. Kinetic energy is not conserved because some is lost as heat and deformation when the blocks stick.

Question 24General Science: Physics and Chemistry Fundamentals

Which quantum number determines the maximum number of orbitals in a given principal shell?

  1. The magnetic quantum number
  2. The spin quantum number
  3. The mass number
  4. The principal quantum number Correct answer.

Explanation

The principal quantum number n fixes the number of subshells and hence the total number of orbitals in a shell, which is n². The magnetic quantum number labels orientation within a subshell, and the spin quantum number describes the two states of an electron.

Question 25General Science: Physics and Chemistry Fundamentals

An ideal gas is compressed isothermally. Which statement is correct?

  1. The gas absorbs heat equal to the work done on it
  2. Heat must flow out of the gas to keep its temperature constant Correct answer.
  3. The internal energy of the gas rises in proportion to the pressure
  4. No work is done on the gas during compression

Explanation

For an ideal gas, internal energy depends only on temperature, so an isothermal process has ΔU = 0. The first law then requires Q = W; since work is done on the gas, an equal amount of heat must leave it to the surroundings.

Question 26General Science: Physics and Chemistry Fundamentals

Which quantity is a vector, having both magnitude and direction?

  1. Velocity Correct answer.
  2. Mass
  3. Temperature
  4. Speed

Explanation

A vector quantity requires both a size and a direction to be fully described. Velocity specifies how fast an object moves and in which direction, so it is a vector. Speed, mass and temperature are scalars, fully described by magnitude alone.

Question 27General Science: Physics and Chemistry Fundamentals

Which of the following is a noble gas with a completely filled outer electron shell?

  1. Sodium
  2. Oxygen
  3. Neon Correct answer.
  4. Chlorine

Explanation

Noble gases in group 18 have full outer shells, which makes them chemically unreactive. Neon has ten electrons arranged as 2, 8, giving a complete second shell. Oxygen, chlorine and sodium all have incomplete outer shells and readily react to achieve stable configurations.

Question 28General Science: Physics and Chemistry Fundamentals

A stone is dropped from rest and falls freely under gravity, taken as 10 m/s². What is its speed after 3 s, ignoring air resistance?

  1. 3 m/s
  2. 10 m/s
  3. 30 m/s Correct answer.
  4. 15 m/s

Explanation

For motion from rest under constant acceleration, speed equals acceleration multiplied by time. Here 10 m/s² × 3 s gives 30 m/s. Air resistance is neglected, so the acceleration stays constant throughout the fall.

Question 29General Science: Physics and Chemistry Fundamentals

Which subatomic particle determines the identity of an element?

  1. Electron
  2. Neutron
  3. Photon
  4. Proton Correct answer.

Explanation

The number of protons in the nucleus, called the atomic number, fixes which element an atom is. Changing the proton count converts the atom into a different element entirely. Neutrons affect mass and isotopes, while electrons govern bonding and charge.

Question 30General Science: Physics and Chemistry Fundamentals

A sample of gas is held at constant temperature while its volume is halved. What happens to its pressure?

  1. It halves
  2. It doubles Correct answer.
  3. It falls to one quarter
  4. It stays the same

Explanation

Boyle's law states that at constant temperature the pressure of a fixed mass of gas is inversely proportional to its volume. Halving the volume therefore doubles the pressure. The product of pressure and volume remains constant throughout the change.

Question 31General Science: Physics and Chemistry Fundamentals

Which type of chemical bond involves the sharing of electron pairs between atoms?

  1. Ionic bond
  2. Covalent bond Correct answer.
  3. Hydrogen bond
  4. Metallic bond

Explanation

A covalent bond forms when two atoms share one or more pairs of electrons, typically between nonmetals. Ionic bonding instead involves complete transfer of electrons and electrostatic attraction. Metallic bonding involves delocalised electrons, and hydrogen bonds are weaker intermolecular attractions.

Question 32General Science: Physics and Chemistry Fundamentals

Which observation shows that a chemical change has taken place rather than a physical one?

  1. Sugar dissolves in water
  2. Ice melts into liquid water
  3. A new gas is released with a different smell Correct answer.
  4. Salt water is heated until the water boils off

Explanation

A chemical change produces new substances with different properties from the starting materials. The appearance of a new gas with a different smell indicates a new product has formed. Melting, dissolving and boiling merely change physical state or dispersion without creating new substances.

Question 33General Science: Physics and Chemistry Fundamentals

A current of 2 A flows through a resistor of 15 Ω. What is the potential difference across it?

  1. 7.5 V
  2. 30 V Correct answer.
  3. 0.13 V
  4. 17 V

Explanation

Ohm's law relates potential difference to current and resistance as V = IR. Multiplying 2 A by 15 Ω gives 30 V. The resistance and current are directly multiplied, not divided.

Question 34General Science: Physics and Chemistry Fundamentals

A force of 20 N acts on a mass of 5 kg on a frictionless surface. What is the resulting acceleration?

  1. 100 m/s²
  2. 4 m/s² Correct answer.
  3. 25 m/s²
  4. 0.25 m/s²

Explanation

Newton's second law gives acceleration as force divided by mass, a = F/m. Dividing 20 N by 5 kg yields 4 m/s². Because the surface is frictionless, the net force equals the applied force.

Question 35General Science: Physics and Chemistry Fundamentals

Which process explains why a wet cloth dries faster on a warm, windy day?

  1. Evaporation speeds up as temperature and airflow increase Correct answer.
  2. Condensation removes water from the cloth
  3. Sublimation turns liquid water directly into vapour
  4. Freezing traps water inside the fibres

Explanation

Evaporation occurs when the fastest surface molecules escape as vapour. Raising the temperature increases the proportion of molecules with enough energy to escape, and wind carries vapour away so it does not recondense. Both effects together speed up drying.

Question 36General Science: Physics and Chemistry Fundamentals

Which statement describes an oxidation reaction in terms of electron transfer?

  1. A species loses electrons and its oxidation number rises Correct answer.
  2. A species loses neutrons and becomes an isotope
  3. A species gains electrons and its oxidation number falls
  4. A species gains protons and becomes more acidic

Explanation

Oxidation is defined as loss of electrons, which increases the oxidation number of the species. Reduction is the opposite process, the gain of electrons. The two always occur together in a redox reaction, balancing electron transfer.

Question 37General Science: Physics and Chemistry Fundamentals

An object is placed 30 cm from a converging lens of focal length 10 cm. Where is the image formed?

  1. 30 cm on the near side of the lens
  2. 15 cm on the far side of the lens Correct answer.
  3. 60 cm on the far side of the lens
  4. 10 cm on the far side of the lens

Explanation

The lens formula gives 1/f = 1/v − 1/u with the sign convention applied. Using u = 30 cm and f = 10 cm gives 1/v = 1/10 − 1/30 = 1/15, so v = 15 cm. The positive result places a real image on the far side of the lens.

Question 38General Science: Physics and Chemistry Fundamentals

A radioactive sample has a half-life of 8 days. What fraction of the original nuclei remains after 24 days?

  1. One eighth Correct answer.
  2. One third
  3. One quarter
  4. One sixteenth

Explanation

The number of half-lives elapsed is 24 divided by 8, which equals three. Each half-life halves the remaining nuclei, so the fraction left is (1/2)³ = 1/8. The decay is exponential rather than linear.

Question 39General Science: Physics and Chemistry Fundamentals

A 0.5 kg ball hits a wall at 4 m/s and rebounds at 3 m/s along the same line. What is the magnitude of its change in momentum?

  1. 0.5 kg·m/s
  2. 3.5 kg·m/s Correct answer.
  3. 2.0 kg·m/s
  4. 7.0 kg·m/s

Explanation

Momentum is mass times velocity, and reversal of direction makes the velocity change equal to 4 + 3 = 7 m/s in magnitude. Multiplying by the mass of 0.5 kg gives 3.5 kg·m/s. Treating the rebound as negative is essential to avoid subtracting incorrectly.

Question 40General Science: Physics and Chemistry Fundamentals

In an electrochemical cell, which change would increase the cell voltage for a given pair of half-cells?

  1. Connecting the two half-cells with a longer wire of the same material
  2. Reducing the surface area of the electrodes in contact with the electrolyte
  3. Increasing the mass of the electrodes without changing their materials
  4. Choosing half-cells with a larger difference in standard electrode potential Correct answer.

Explanation

The standard cell potential equals the reduction potential of the cathode minus that of the anode. A larger difference between the two electrode potentials therefore gives a larger voltage. Electrode mass, surface area and wire length affect current capacity or resistance, not the thermodynamic cell potential.

Question 41Biology, Life Sciences and Public Health

Which molecule carries the genetic instructions from DNA to the ribosome during protein synthesis?

  1. Deoxyribose sugar
  2. Transfer RNA
  3. Ribosomal RNA
  4. Messenger RNA Correct answer.

Explanation

Messenger RNA is transcribed from a gene and transports that coded sequence to the ribosome, where it is translated into a chain of amino acids. Transfer RNA brings amino acids, and ribosomal RNA forms part of the ribosome itself, so neither serves as the carrier of the message.

Question 42Biology, Life Sciences and Public Health

A person with blood group AB can receive red cells from which donors without a transfusion reaction?

  1. Group B only
  2. Group A only
  3. Groups A, B, AB and O Correct answer.
  4. Group O only

Explanation

Group AB plasma contains neither anti-A nor anti-B antibodies, so the recipient's immune system will not attack red cells bearing either antigen. People with group AB are therefore often called universal recipients of red cells, though cross-matching is still performed in practice.

Question 43Biology, Life Sciences and Public Health

Which structure in the human kidney is the primary site of glomerular filtration?

  1. Renal pelvis
  2. Loop of Henle
  3. Glomerulus Correct answer.
  4. Collecting duct

Explanation

The glomerulus is a tuft of capillaries where hydrostatic pressure forces water and small solutes out of the blood into Bowman's capsule, forming the filtrate. The loop of Henle and collecting duct act later on that filtrate to reabsorb water and ions.

Question 44Biology, Life Sciences and Public Health

Which vitamin deficiency classically causes night blindness and dry eyes?

  1. Vitamin D
  2. Vitamin K
  3. Vitamin A Correct answer.
  4. Vitamin C

Explanation

Vitamin A is needed to make rhodopsin, the light-sensitive pigment in rod cells, so deficiency impairs vision in dim light. It also maintains the epithelial lining of the eye, and its lack leads to dryness of the conjunctiva and cornea.

Question 45Biology, Life Sciences and Public Health

In a monohybrid cross between two heterozygous pea plants (Aa x Aa), what proportion of offspring is expected to show the recessive phenotype?

  1. One half
  2. Three quarters
  3. All offspring
  4. One quarter Correct answer.

Explanation

The cross yields genotypes in the ratio 1 AA : 2 Aa : 1 aa, and only the aa genotype expresses the recessive trait. That genotype accounts for one of four equally likely outcomes, so one quarter of the offspring show the recessive phenotype.

Question 46Biology, Life Sciences and Public Health

Which type of pathogen causes malaria in humans?

  1. A fungus
  2. A virus
  3. A bacterium
  4. A protozoan parasite Correct answer.

Explanation

Malaria is caused by species of Plasmodium, a single-celled protozoan parasite that is transmitted by the bite of an infected female Anopheles mosquito. It is not a bacterium, fungus or virus, which is why antibacterial and antifungal drugs do not treat it.

Question 47Biology, Life Sciences and Public Health

Which gas is the main product released when yeast ferments glucose anaerobically?

  1. Methane
  2. Oxygen
  3. Nitrogen
  4. Carbon dioxide Correct answer.

Explanation

In anaerobic fermentation yeast converts glucose mainly to ethanol and carbon dioxide, releasing energy without oxygen. The carbon dioxide is what makes bread dough rise and forms bubbles in fermenting liquids.

Question 48Biology, Life Sciences and Public Health

Which of the following is a vector-borne disease transmitted by mosquitoes?

  1. Cholera
  2. Dengue fever Correct answer.
  3. Tetanus
  4. Tuberculosis

Explanation

Dengue fever is caused by a virus spread mainly by Aedes mosquitoes, which act as the vector between infected and susceptible people. The other diseases are transmitted through contaminated wounds, water or food, or airborne droplets rather than by insect bites.

Question 49Biology, Life Sciences and Public Health

During which phase of mitosis do chromosomes align along the equator of the cell?

  1. Prophase
  2. Anaphase
  3. Telophase
  4. Metaphase Correct answer.

Explanation

In metaphase the condensed chromosomes line up at the cell equator, called the metaphase plate, before being pulled apart. This alignment ensures that each daughter cell will receive one copy of every chromosome during the following anaphase.

Question 50Biology, Life Sciences and Public Health

A mother who is a carrier of an X-linked recessive disorder has children with an unaffected father. What is the probability that a son will be affected?

  1. Zero
  2. One half Correct answer.
  3. One quarter
  4. All sons

Explanation

A son inherits his single X chromosome from his mother and a Y from his father, so his status depends entirely on which maternal X he receives. A carrier mother has one normal and one affected X, giving each son a one-in-two chance of inheriting the affected allele and being affected.