1st Year Chemistry Chapter 6 TestChemical Energetics

Q1. Multiple choice questions (Attempt all · 10 × 1 = 10)

1. An energy profile shows a very flat region after the first peak before rising to a second, higher peak; what does this suggest about the intermediate?

   1. It is highly reactive.

   2. It is consumed quickly.

   3. It is relatively stable.

   4. It has a high activation energy for the next step.

2. Which of the following factors would lead to a greater enthalpy change of hydration(more exothermic)?

   1. A larger ionic radius and a smaller charge

   2. A smaller ionic radius and a smaller charge

   3. A larger ionic radius and a larger charge

   4. A smaller ionic radius and a larger charge

3. If the calorie content of a food is given as 500 Calories, what does this value fundamentally represent in terms of energy change?

   1. The maximum work the body can derive from that food.

   2. The total heat released when food is completely metabolized.

   3. The change in internal energy of the food during digestion.

   4. The activation energy required to break down the food molecules.

4. In a bomb calorimeter, which quantity is held constant during the measurement of enthalpy change?

   1. Pressure

   2. Temperature

   3. Volume

   4. Heat

5. The change in heat energy of a chemical reaction at constant temperature and pressure is called:

   1. Enthalpy change

   2. Heat of sublimation

   3. Bond energy

   4. Internal energy change

6. In endothermic reactions, the heat contents of the:

   1. Products is more than that of reactants.

   2. Reactants is more than that of products

   3. Both (A) and (B)

   4. Products is equal to reactants

7. A catalyst provides a multi-step pathway with lower activation energy; how does the number of transition states compare to the uncatalyzed one-step reaction?

   1. The number of transition states remains the same.

   2. The number of transition states decreases.

   3. The number of transition states increases.

   4. The number of transition states depends on the sign of _.

8. Which of the following equations represents standard heat of formation of C₂H₄?

   1. 

   2. 

   3. 

   4. 

9.  Hess's Law is a direct consequence of which fundamental thermodynamic principle?

   1. The First Law of Thermodynamics (conservation of energy)

   2. The Second Law of Thermodynamics (entropy increase)

   3. The Third Law of Thermodynamics (absolute zero entropy)

   4. Le Chatelier's Principle (equilibrium shifts)

10. Which of the following substances would you expect to have the highest standard molar entropy (S ^o) at 298 K?

    1. H ₂ O _(l)

    2. NaCl_(s)

    3. O_2(g)

    4. C(diamond