AKU Entry Test Chemistry: Fundamental Concepts MCQs

AKU Entry Test Chemistry: Fundamental Concepts MCQs — sample questions

1. Question 1

   Q1. The smallest particle of an element that retains its chemical properties is called?

   • A) Molecule
   • B) Atom
   • C) Ion
   • D) Compound

   Answer: Atom

   Explanation: Atom is the smallest unit of an element; 'Molecule' is a group of atoms, 'Ion' is a charged atom.

2. Question 2

   Q2. Which quantity is a fundamental physical quantity in the SI system?

   • A) Length
   • B) Volume
   • C) Density
   • D) Speed

   Answer: Length

   Explanation: Length is a fundamental quantity; 'Volume', 'Density', and 'Speed' are derived quantities.

3. Question 3

   Q3. The mass of one mole of a substance is equal to its?

   • A) Molecular mass
   • B) Atomic mass
   • C) Molar mass
   • D) Equivalent mass

   Answer: Molar mass

   Explanation: Molar mass is the mass of one mole; 'Molecular mass' is for molecules, 'Atomic mass' is for atoms.

4. Question 4

   Q4. A solution contains 40g of NaOH in 1000g of water. What is its percentage by mass?

   • A) 3.85%
   • B) 4.0%
   • C) 4.08%
   • D) 4.16%

   Answer: 3.85%

   Explanation: Percentage by mass = (mass of solute / total mass) * 100 = (40 / (40 + 1000)) * 100.

5. Question 5

   Q5. The empirical formula of a compound is CH2O. Its molecular formula could be?

   • A) C2H4O2
   • B) C3H6O3
   • C) C4H8O4
   • D) All of the above are possible

   Answer: All of the above are possible

   Explanation: Empirical formula is the simplest whole number ratio; molecular formula is a multiple of it.

6. Question 6

   Q6. The number of significant figures in 0.005060 is?

   • A) 4
   • B) 5
   • C) 3
   • D) 7

   Answer: 4

   Explanation: Significant figures include all certain digits and one uncertain digit; leading zeros are not significant.

7. Question 7

   Q7. What is the oxidation state of Mn in KMnO4?

   • A) +6
   • B) +7
   • C) +5
   • D) +4

   Answer: +7

   Explanation: Oxidation state of Mn is calculated as: +1 (K) + x (Mn) + 4(-2) (O) = 0.

8. Question 8

   Q8. The process of converting a liquid to a gas at its boiling point is called?

   • A) Evaporation
   • B) Sublimation
   • C) Vaporization
   • D) Condensation

   Answer: Vaporization

   Explanation: Vaporization occurs at boiling point; 'Evaporation' occurs at surface below boiling point.

9. Question 9

   Q9. What is the pH of a neutral solution at 25°C?

   • A) 6
   • B) 7
   • C) 8
   • D) 0

   Answer: 7

   Explanation: pH of neutral solution is 7 at 25°C; it changes with temperature.

10. Question 10

    Q10. The reaction between an acid and a base to form salt and water is called?

    • A) Neutralization
    • B) Hydrolysis
    • C) Electrolysis
    • D) Ionization

    Answer: Neutralization

    Explanation: Neutralization reaction produces salt and water; 'Hydrolysis' involves water breaking a compound.

11. Question 11

    Q11. A buffer solution resists changes in?

    • A) pH
    • B) Temperature
    • C) Concentration
    • D) Volume

    Answer: pH

    Explanation: Buffer solution maintains pH; it doesn't significantly resist changes in temperature, concentration, or volume.

12. Question 12

    Q12. The energy required to remove an electron from an isolated gaseous atom is called?

    • A) Electron Affinity
    • B) Ionization Energy
    • C) Electronegativity
    • D) Atomic Radius

    Answer: Ionization Energy

    Explanation: Ionization energy is the energy to remove an electron; 'Electron affinity' is energy released when an electron is added.

13. Question 13

    Q13. The type of bond formed between two atoms with a large difference in electronegativity is?

    • A) Covalent
    • B) Ionic
    • C) Metallic
    • D) Hydrogen

    Answer: Ionic

    Explanation: Large electronegativity difference leads to 'Ionic' bond; 'Covalent' bond forms with small or no difference.

14. Question 14

    Q14. The temperature at which the vapor pressure of a liquid equals the atmospheric pressure is its?

    • A) Boiling Point
    • B) Melting Point
    • C) Critical Temperature
    • D) Triple Point

    Answer: Boiling Point

    Explanation: Boiling occurs when vapor pressure equals atmospheric pressure; 'Melting point' is for solid to liquid transition.

15. Question 15

    Q15. A catalyst increases the rate of a reaction by?

    • A) Lowering the activation energy
    • B) Increasing the activation energy
    • C) Changing the equilibrium constant
    • D) Increasing the concentration of reactants

    Answer: Lowering the activation energy

    Explanation: Catalyst lowers activation energy; it doesn't change equilibrium constant or concentration.

16. Question 16

    Q16. The principle that 'the total entropy of an isolated system can never decrease over time' is a statement of?

    • A) First Law of Thermodynamics
    • B) Second Law of Thermodynamics
    • C) Third Law of Thermodynamics
    • D) Zeroth Law of Thermodynamics

    Answer: Second Law of Thermodynamics

    Explanation: Second Law states that total entropy of an isolated system always increases or remains constant.

17. Question 17

    Q17. The process by which a solid changes directly into vapor is called?

    • A) Sublimation
    • B) Deposition
    • C) Evaporation
    • D) Condensation

    Answer: Sublimation

    Explanation: Sublimation is the transition from solid to gas; 'Deposition' is the reverse process.

18. Question 18

    Q18. What is the hybridization of the carbon atom in methane (CH4)?

    • A) sp
    • B) sp2
    • C) sp3
    • D) dsp3

    Answer: sp3

    Explanation: Methane's carbon is sp3 hybridized; it has four equivalent bonds.

19. Question 19

    Q19. The quantum number that describes the shape of an orbital is?

    • A) n
    • B) l
    • C) m
    • D) s

    Answer: l

    Explanation: 'l' (azimuthal quantum number) determines the orbital shape; 'n' is principal quantum number.

20. Question 20

    Q20. A solution is prepared by dissolving 12 g of urea (molar mass = 60 g/mol) in 1000 g of water. What is the molality of the solution?

    • A) 0.2 m
    • B) 0.4 m
    • C) 0.6 m
    • D) 0.8 m

    Answer: 0.2 m

    Explanation: Molality = moles of solute / kg of solvent. 12/60 = 0.2 mol in 1 kg. Option D ignores kg of solvent.