All Free Chemistry MCQs with Answers

• A. 35-50°C
• B. 130-150°C
• C. 400-450°C
• D. 500-600°C

Explanation: Option C is correct. The optimum temperature for the Haber process is 400-450°C.

• A. Jg-1K-1
• B. JK-1
• C. JmolK-1
• D. KJ/mol

Explanation: The correct answer is Jg-1K-1, which is the SI unit of specific heat capacity.

• A. 4.2 kJ/mol/K
• B. 4.2 j/g.K
• C. 4.61/g/K
• D. 42/g/K

Explanation: The specific heat capacity of water is approximately 4.2 joules per gram per degree Celsius (J/g/°C).

• A. E = q+w
• B. E = q+(-w)
• C. E= (-q)+(-w)
• D. E = (-q)+w

Explanation: According to the first law of thermodynamics:ΔE=q+wq = heat absorbed by the system (positive if absorbed, negative if released)w= work…

• A. Equal to delta H
• B. More than delta H
• C. Less than delta H
• D. Zero

Explanation: For an endothermic reaction, the enthalpy of reaction (ΔH) is positive, indicating that energy is absorbed during the reaction.

• A. Molar heat of sublimation
• B. Heat of vaporisation
• C. Latent heat of fusion
• D. Heat capacity

Explanation: The heat of vaporization is the amount of heat energy required to change one mole of a liquid into a gas at its boiling point, without any…

• A. Diamond
• B. Graphite
• C. Peat
• D. Coa

Explanation: Graphite - Correct. Graphite is the most stable allotrope of carbon due to its lower Gibbs free energy.

• A. Henry's law
• B. Second law of thermodynamics
• C. First law of thermodynamics
• D. Second law of thermochemistry

Explanation: First law of thermodynamics - Correct. Hess's law is based on the conservation of energy, which aligns with the first law.

• A. Combustion of methane
• B. Decomposition of water
• C. Dehydrogenation of ethane or ethylene
• D. Conversion of graphite

Explanation: Combustion of methane releases energy, making it an exothermic reaction.

• A. ΔE+W
• B. qv = E +PΔV
• C. qv= E+W
• D. qv = E
• E. qv = PΔGV

Explanation: The equation of the first law of thermodynamics, q = ΔE + W, reduces at constant volume to qv = ΔE.At constant volume (no work is done)…

• A. Second order
• B. First order
• C. Half order
• D. Third order
• E. Zero order

Explanation: The correct answer is e) Zero order. The given reaction H2 + Cl2 -> 2HCl is a zero-order reaction, where the reaction rate is independent…

• A. Lussac's law of combining volume
• B. Hess's law
• C. Boyle's law
• D. Charle's law
• E. Avagadro's law

Explanation: Hess's law states that the enthalpy change of a reaction is independent of the pathway taken from reactants to products.

• A. Same
• B. Sometimes decreases sometimes increases
• C. Reaction moves backward
• D. Decreases
• E. Increases

Explanation: In exothermic reactions Kc is inversely proportional to temperature it mean when temperature will increase Kc will decrease and when…

• A. 0.0821 joules
• B. 8.314 dm3-atm
• C. 0.0821 KJ
• D. 0.0821 dm³-atm

Explanation: One mole of an ideal gas at 273.16 K and one atmospheric pressure and its temperature is increased by 1K, then it will absorb 0.0821…

• A. Henry's law
• B. Le - Chatleir's Principle
• C. Hess's law
• D. Common Ion effect

Explanation: The Born-Haber cycle is a thermodynamic cycle used to determine the lattice energy of ionic compounds, which is the energy required to…

• A. Freezing
• B. Decomposition
• C. Sublimation
• D. Enthalpy

Explanation: Enthalpy is a state function. State functions are properties that depend only on the current state of a system and are independent of the…

• A. Refrigerant
• B. A solvent
• C. Insecticides
• D. A fire extinguisher

Explanation: Freon is commonly known as refrigerant. Refrigerants are substances used in refrigeration systems and air conditioning units to transfer…

• A. Isolated system
• B. Closed system
• C. Open system
• D. Adiabatic system

Explanation: An open system can exchange both energy and matter with its surroundings.

• A. Specific heat
• B. Heat capacity
• C. Latent heat
• D. Internal energy

Explanation: Internal energy U of a system or a body with well-defined boundaries is the total of the kinetic energy due to the motion of molecules and…

• A. Better yield
• B. Lower yeild
• C. Lower rate
• D. Cost change

Explanation: Increasing the pressure increases the yield in Haber's process because the number of moles of products is less than the number of moles of…