NEET: Chemistry MCQs (Practice-Test 1 of 31)

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  1. For a process at 451 K and constant pressure, Ssurr is-326 J K − 1. Calculate the quantity of heat (in kJ) absorbed by the system.

    1. N/A

    2. N/A

    3. N/A

    4. N/A

  2. Which of the following produces an INCREASE in entropy of the system?

    1. H2O (l) → H2O (s)

    2. 2O2 (g) + 2SO (g) → 2SO3 (g)

    3. 2CH3OH (g) + 3O2 (g) → 2CO2 (g) + 4H2O (l)

    4. I2 (s) → I2 (l)

    5. None of the above:

  3. The gas-phase reaction between H2 and Cl2 can be initiated by ultraviolet light at 25oC, H2 (g) + Cl2 (g) → 2HCl (g) Using the thermodynamic data provided below, calculate the standard free energy change (in kJ) at 25oC for this reaction. Compound Hfo, kJ mol-1So, J mol-1 K − 1 H20130.57 Cl20222.96 HCl-92.307186. 80

    1. N/A

    2. N/A

    3. N/A

    4. N/A

  4. In lecture, you observed the following reaction, For this reaction, Ho = -241.8 kJ and So = -88.8 J K − 1. Assuming that Ho = H and So = S at all temperatures, calculate the temperature (in K) at which this reaction would become non-spontaneous.

    1. N/A

    2. N/A

    3. N/A

    4. N/A

  5. For a particular chemical reaction at 400oC, G = -67 kJ. Calculate the time (in seconds) it will take for the reaction to reach completion.

    1. N/A

    2. N/A

    3. N/A

    4. N/A

  6. For a particular chemical reaction, Ho is positive and So is negative. Which of the following statements about the spontaneity of the reaction under standard conditions is TRUE?

    1. The reaction will be spontaneous only if the magnitude of Ho is large enough to overcome the unfavorable entropy change.

    2. The reaction will be spontaneous only if the magnitude of So is large enough to overcome the unfavorable enthalpy change.

    3. The reaction will be spontaneous regardless of the magnitudes of Ho and So.

    4. The reaction cannot be spontaneous.

    5. The reaction will be spontaneous only of Go is positive.

  7. Which of the following is TRUE for an operating voltaic cell?

    1. G > 0; E = 0

    2. G < 0; E < 0

    3. G = 0; E > 0

    4. G = 0; E = 0

    5. G < 0; E > 0

  8. Which of the following produces a DECREASE in entropy of the system? Hint: The system is shown in bold.

    1. Dissolving sugar in a cup of coffee.

    2. Condensation of water on the surface of a glass of iced tea on a hot summer day.

    3. Boiling water in a pot on the stove to make spaghetti.

    4. Allowing the liquid propane in a gas grill to escape from the tank.

    5. Producing CO2 gas from baking soda (NaHCO3) when baking a cake.

  9. Consider the following reaction and thermodynamic data, 2H2O2 (aq) ⇔ 2H2O (l) + O2 (g) substance Hfo, kJ mol-1So, J mol-1 K − 1, H2O2 (aq) -191.17143. 9, H2O (l) -285.8369. 91, O2 (g) 0205.14 Calculate the value (in kJ) of Go at 25oC.

  10. For a particular chemical reaction, both Ho and So are negative. Which of the following statements about the spontaneity of the reaction under standard conditions is TRUE?

    1. The reaction will be spontaneous only if the magnitude of Ho is large enough to overcome the unfavorable entropy change.

    2. The reaction will be spontaneous only if the magnitude of So is large enough to overcome the unfavorable enthalpy change.

    3. The reaction will be spontaneous regardless of the magnitudes of Ho and So.

    4. The reaction cannot be spontaneous.

    5. The reaction will be spontaneous only of Go is positive.

  11. The boiling point of a substance is the temperature at which equilibrium is established between the liquid and the vapor. CH3CH2OH (l) ⇔ CH3CH2OH (g) Calculate the boiling point (in K) of ethanol, CH3CH2OH, if H = 42.6 kJ and S = 122 J/K for this process.

    1. N/A

    2. N/A

    3. N/A

    4. N/A

  12. What is the significance of the Third Law of Thermodynamics? Choose the best answer.

    1. The absolute entropy of a substance decreases with increasing temperature.

    2. The change in entropy of the universe must be positive for a spontaneous process.

    3. The absolute value of entropy can be measured for some very pure substances.

    4. The change in entropy of the universe equals the sum of the change in entropy of the system plus the change in entropy of the surroundings.

    5. The entropy of the universe is constant.

  13. The Ksp for the sparingly soluble salt barium chromate (BaCrO4) at 25oC is equal to 2.0 × 10 − 10. Calculate Go (in kJ) for the following reaction. BaCrO4 (s) ⇔ Ba2 + (aq) + CrO42- (aq)

    1. N/A

    2. N/A

    3. N/A

    4. N/A

  14. A Chemistry 116 student determined the value of Ksp for a saturated solution of borax at several different temperatures. The value for Sofor the dissolution of borax in water can be determined from:

    1. the slope of the line resulting from a plot of ln Ksp versus (1/T)

    2. the y-intercept of the line resulting from a plot of ln Ksp versus T

    3. the slope of the line resulting from a plot of Ksp versus (1/T)

    4. the y-intercept of the line resulting from a plot of ln Ksp versus (1/T)

    5. the slope of the curve at 25oC from a plot of ln Ksp versus T

  15. Consider the following gas-phase reaction, 2NO2 (g) ⇔ 2NO (g) + O2 (g), Go = + 70.5 kJ, If 1.00 mole of NO2 (g) is placed in a 1.00 − L flask (no NO (g) or O2 (g) initially) at 25oC, which of the following statements is TRUE?

    1. The reaction will occur spontaneously from left to right.

    2. The reaction will occur spontaneously from right to left.

    3. The reaction is not spontaneous in either direction.

    4. The reaction is spontaneous in both directions.

Discussions & Questions

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