231.
A fixed mass $$'m'$$ of a gas is subjected to transformation
of states from $$K$$ to $$L$$ to $$M$$ to $$N$$ and back to $$K$$ as shown in the figure :
The pair of isochoric processes among the transformation of states is
A
$$K$$ to $$L$$ and $$L$$ to $$M$$
B
$$L$$ to $$M$$ and $$N$$ to $$K$$
C
$$L$$ to $$M$$ and $$M$$ to $$N$$
D
$$M$$ to $$N$$ and $$N$$ to $$K$$
Answer :
$$L$$ to $$M$$ and $$N$$ to $$K$$
232. Enthalpy of the reaction, $$C{H_4} + \frac{1}{2}{O_2} \to C{H_3}OH,$$ is negative. If enthalpy of combustion of $$C{H_4}$$ and $$C{H_3}OH$$ are $$x$$ and $$y$$ respectively, then which relation is correct?
A
$$x > y$$
B
$$x < y$$
C
$$x = y$$
D
$$x \geqslant y$$
Answer :
$$x < y$$
233.
The given enthalpy diagram represents which of the following reactions ?
A
Enthalpy diagram for endothermic reaction
B
Enthalpy diagram for exothermic reaction
C
Enthalpy diagram for reversible reaction
D
Enthalpy diagram for non-spontaneous reaction
Answer :
Enthalpy diagram for exothermic reaction
234. One mole of a non-ideal gas undergoes a change of state ( $${2.0\,atm,\,3.0L,\,95\left( K \right)}$$ → ( $${4.0\,atm,\,5.0L,\,245K}$$ ) with a change in internal energy, $$\Delta U = 30.0\,L\,atm\,.$$ The change in enthalpy $$\left( {\Delta H} \right)$$ of the process in $$L$$ atm is
A
40.0
B
42.3
C
44.0
D
not defined, because pressure is not constant
Answer :
44.0
235. Standard enthalpy and standard entropy changes for the oxidation of ammonia at $$298\,K$$ are $$ - 382.64\,kJ\,mo{l^{ - 1}}$$ and $$ - 45.6\,J{K^{ - 1}}\,mo{l^{ - 1}},$$ respectively. Standard Gibb's energy change for the same reaction at $$298\,K$$ is
A
$$ - 22.1\,kJ\,mo{l^{ - 1}}$$
B
$$ - 339.3\,kJ\,mo{l^{ - 1}}$$
C
$$ - 439.3\,kJ\,mo{l^{ - 1}}$$
D
$$ - 523.2\,kJ\,mo{l^{ - 1}}$$
Answer :
$$ - 339.3\,kJ\,mo{l^{ - 1}}$$
236. Consider the $$\Delta G_f^ \circ $$ and $$\Delta H_f^ \circ \left( {kJ/mol} \right)$$ for the following oxides. Which oxide can be most easily decomposed to form the metal and oxygen gas?
A
$$ZnO\left( {\Delta {G^ \circ } = - 318.4,\Delta {H^ \circ } = - 348.3} \right)$$
B
$$C{u_2}O\left( {\Delta {G^ \circ } = - 146.0,\Delta {H^ \circ } = - 168.8} \right)$$
C
$$HgO\left( {\Delta {G^ \circ } = - 58.5,\Delta {H^ \circ } = - 90.8} \right)$$
D
$$PbO\left( {\Delta {G^ \circ } = - 187.9,\Delta {H^ \circ } = - 217.3} \right)$$
Answer :
$$HgO\left( {\Delta {G^ \circ } = - 58.5,\Delta {H^ \circ } = - 90.8} \right)$$
237.
What will be the amount of heat evolved by burning $$10\,L$$ of methane under standard conditions ?
( Given heats of formation of $$C{H_4},C{O_2}$$ and $${H_2}O$$ are $$ - 76.2, - 398.8$$ and $$ - 241.6\,kJ\,mo{l^{ - 1}}$$ respectively. )
A
$$805.8\,kJ$$
B
$$398.8\,kJ$$
C
$$359.7\,kJ$$
D
$$640.4\,kJ$$
Answer :
$$359.7\,kJ$$
238. In an endothermic reaction, the value of $$\Delta H$$ is
A
zero
B
positive
C
negative
D
constant
Answer :
positive
239. Standard Gibb’s free energy change for isomerization reaction $$cis{\text{ - }}2{\text{ - pentene}} \rightleftharpoons trans{\text{ - }}2{\text{ - pentene}}$$ is $$ - 3.67\,kJ/mol$$ at $$400\,K.$$ If more $$trans{\text{ - }}2{\text{ - pentene}}$$ is added to the reaction vessel, then
A
more $$cis{\text{ - }}2{\text{ - pentene}}$$ is formed
B
equilibrium remains unaffected
C
additional $$trans{\text{ - }}2{\text{ - pentene}}$$ is formed
D
equilibrium is shifted in forward direction
Answer :
more $$cis{\text{ - }}2{\text{ - pentene}}$$ is formed
240.
For combustion of $$1\,mole$$ of benzene at $$25{\,^ \circ }C,$$ the heat of reaction at constant pressure is $$ - 780.9\,kcal.$$ What will be the heat of reaction at constant volume ?
$${C_6}{H_{6\left( l \right)}} + 7\frac{1}{2}{O_{2\left( g \right)}} \to 6C{O_{2\left( g \right)}} + 3{H_2}{O_{\left( l \right)}}$$
A
$$ - 781.8\,kcal$$
B
$$ - 780.0\,kcal$$
C
$$ + 781.8\,kcal$$
D
$$ + 780.0\,kcal$$
Answer :
$$ - 780.0\,kcal$$