All Free Chemistry MCQs with Answers
Every Chemistry question in the bank, across all chapters, each with the correct answer and a written explanation. Free and unlimited, with no account needed.
13,720 questions · page 591 of 686
- A. Total energy of the system and surrounding is conserved
- B. Energy can neither be created nor destroyed
- C. It is the same as law of conservation of energy
- D. Total energy of the system is increasing
Explanation: The total energy of the system remains constant. Hence, statement D is not correct.
Correct answer: Total energy of the system is increasing- A. decreasing the activation energy
- B. decreasing the concentration of reactants
- C. decreasing the temperature
- D. increasing the temperature
Explanation: A catalyst increases the rate of reaction in both forward and backward directions by providing an alternate pathway with lower activation…
Correct answer: decreasing the activation energy- A. Total heat
- B. Work done
- C. Entropy
- D. Internal energy
Explanation: For an isochoric process, the volume remains constant. Since; Work done = PΔV, for constant volume, ΔV= 0,, hence work done has a constant…
Correct answer: Work done- A. Al2O3
- B. B2O3
- C. CO
- D. All of these options are correct
Explanation: Frankly speaking, We don't know the absolute enthalpy of a substance because we don't know where absolute Zero is.
Correct answer: All of these options are correct- A. Spontaneous reaction
- B. Exothermic Reaction
- C. Reversible Reaction
- D. Combustion Reaction
Explanation: OPTION A: Because ∆G =∆H - T∆S at this temperature ∆G = 0, indicating that the liquid and vapor phases are in equilibrium.
Correct answer: Spontaneous reaction- A. Rotational & Vibrational
- B. Translation & Rotational
- C. Rotational, Vibrational, and Translation
- D. All of these
Explanation: The kinetic energy of an object with translational and rotational motion is the sum of its translational and its rotational kinetic…
Correct answer: Rotational, Vibrational, and Translation- A. Exothermic reaction
- B. Endothermic reaction
- C. Spontaneous reaction
- D. Nonspontaneous reaction
Explanation: The term exothermic process describes a process or reaction that releases energy from the system to its surroundings, usually in the form…
Correct answer: Exothermic reaction- A. q=m s ∆T
- B. E=q m ∆T
- C. E=m s ∆T
- D. E=m c ∆T
Explanation: Q=ms ∆T is the equation of specific heat. Each term in the equation has a different significance.
Correct answer: q=m s ∆T- A. -394 kJ/mole
- B. +394 kJ/mole
- C. -294 kJ/mole
- D. -390 kJ/mole
Explanation: The heat of formation (∆Hf°) for carbon dioxide (CO2) is: ∆Hf° = -394 kj/mol The negative sign indicates that the formation of one…
Correct answer: -394 kJ/mole- A. Heat is evolved
- B. Heat is absorbed
- C. Heat may evolved or absorbed
- D. Electrolyte do not dissolve in water
Explanation: A solution is a homogeneous mixture of two or more substances and can either be in the gas phase, the liquid phase, or the solid phase.
Correct answer: Heat may evolved or absorbed- A. Electron affinity
- B. Lattice energy
- C. Crystal energy
- D. All of the above
Explanation: As we know that the electron affinity can be calculated by using Born Haber cycle.
Correct answer: All of the above- A. The reaction proceeds in the forward direction at 300 K
- B. At 1200 K, reaction proceeds in the reverse direction
- C. At 300 K, Kp > 1
- D. At 300 K, the products will be favoured more than reactants at equilibrium
Explanation: is incorrect. As in an exothermic reaction, when temperature is decreased reaction shifts towards product side and thus Kp <1 .
Correct answer: At 300 K, Kp > 1- A. The thermodynamics first law is not sufficient to predict the direction of the process
- B. In the case of an exothermic reaction, the overall enthalpy of the products is greater than that of reactants
- C. For the reaction H2(g) + Br2(l) → 2HBr (g) from the bond enthaly data, It is possible to calculate the value of H
- D. At 298K and 1 atmpressure, diamond's standard enthalpy is zero
Explanation: The first law of thermodynamics, which states that energy cannot be created or destroyed, but can be converted from one form to another…
Correct answer: The thermodynamics first law is not sufficient to predict the direction of the process- A. ΔH is positive for exothermic reaction
- B. ΔH is negative for endothermic reactions
- C. The heat of neutralization of strong acid with strong base is always the same
- D. The enthalpy of fusion is negative
Explanation: Enthalpy of neutralization is merely the heat of formation of liquid water from its ionic components.
Correct answer: The heat of neutralization of strong acid with strong base is always the same- A. ΔHf
- B. ΔHc
- C. ΔHsol
- D. Both A and C
Explanation: ΔHf may be +ve or-veΔHsol may be +ve or-veΔHc = always-veΔHat= always +ve
Correct answer: Both A and C- A. ΔH=ΔE+PΔV
- B. ΔH=ΔE-ΔnRT
- C. ΔE=ΔH+ΔP
- D. ΔH=ΔE-PΔV
Explanation: The enthalpy changes of a process is given by following relation: ΔH=ΔE+PΔV
Correct answer: ΔH=ΔE+PΔV- A. 273 K
- B. 373K
- C. 298K
- D. 473K
Explanation: Standard conditions for enthalpy measurement are given below:Temperature=25°C (298 K), Pressure= 1 atm
Correct answer: 298K- A. ∆H° of the reaction depends on temperature
- B. ∆H° of reaction can be > or < zero
- C. ∆H° of catalyzed and uncatalyzed reaction is same
- D. ∆H° is always < 0
Explanation: For endothermic reactions, ∆H° is greater than 0. Hence option D is false and is the correct answer.
Correct answer: ∆H° is always < 0- A. Spontaneous reaction
- B. Rate of reaction
- C. Heat of reaction
- D. Entropy of reaction
Explanation: The branch of thermodynamics does not directly deal with the rate of reaction. Hence, B is the correct option.
Correct answer: Rate of reaction- A. E
- B. G
- C. H
- D. q
Explanation: Option D, q (heat), is correct because it is not a state function.A state function is a property that depends only on the current state of…
Correct answer: q