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10
MCQ (Single Correct Answer)

On the basis of theromochemical equations (1), (2) and (3), find out which of the algebraic relationships given in options (a) to (d) is correct

1. C (graphite) $+\mathrm{O}_2(\mathrm{~g}) \rightarrow \mathrm{CO}_2(\mathrm{~g}) ; \Delta_r H=x \mathrm{~kJ} \mathrm{~mol}^{-1}$

2. C (graphite) $+\frac{1}{2} \mathrm{O}_2(\mathrm{~g}) \rightarrow \mathrm{CO}(\mathrm{g}) ; \Delta_r H=y \mathrm{~kJ} \mathrm{~mol}^{-1}$

3. $\mathrm{CO}(\mathrm{g})+\frac{1}{2} \mathrm{O}_2(\mathrm{~g}) \rightarrow \mathrm{CO}_2(\mathrm{~g}) ; \Delta_r H=z \mathrm{~kJ} \mathrm{~mol}^{-1}$

A
$z=x+y$
B
$x=y-z$
C
$x=y+z$
D
$y=2 z-x$
11
MCQ (Single Correct Answer)

Consider the reactions given below. On the basis of these reactions find out which of the algebraic relationship given in options (a) to (d) is correct?

1. $\mathrm{C}(\mathrm{g})+4 \mathrm{H}(\mathrm{g}) \rightarrow \mathrm{CH}_4(\mathrm{~g}) ; \Delta_r H=x \mathrm{~kJ} \mathrm{~mol}^{-1}$

2. C (graphite) $+2 \mathrm{H}_2(\mathrm{~g}) \rightarrow \mathrm{CH}_4(\mathrm{~g}) ; \Delta_r H=y \mathrm{~kJ} \mathrm{~mol}^{-1}$

A
$x=y$
B
$x=2 y$
C
$x>y$
D
$x< y$
12
MCQ (Single Correct Answer)

The enthalpies of elements in their standard states are taken as zero. The enthalpy of formation of a compound

A
is always negative
B
is always positive
C
may be positive or negative
D
is never negative
13
MCQ (Single Correct Answer)

Enthalpy of sublimation of a substance is equal to

A
enthalpy of fusion + enthalpy of vaporisation
B
enthalpy of fusion
C
enthalpy of vaporisation
D
twice the enthalpy of vaporisation
14
MCQ (Single Correct Answer)

Which of the following is not correct?

A
$\Delta G$ is zero for a reversible reaction.
B
$\Delta G$ is positive for a spontaneous reaction.
C
$\Delta G$ is negative for a spontaneous reaction.
D
$\Delta G$ is positive for a non-spontaneous reaction.
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