Equal volumes of monoatomic and diatomic gases at same initial temperature and pressure are mixed. The ratio of specific heats of the mixture (C_p/C_v) will be [AFMC 2002]

(1) 1

(2) 2

(3) 1.67

(4) 1.5

The unit of entropy is -

1. J mol^–1

2. JK mol^–1

3. J mol^–1 K^–1

4. J^–1 K^–1 mol^–1

The entropy changed involved in the conversion of 1 mole of liquid water at 373 K to vapour at the same temperature will be $[\Delta H_{\text{vap}}=2.257kJ/gm]$ [MP PET 2002]

(1) 0.119 kJ

(2) 0.109 kJ

(3) 0.129 kJ

(4) 0.120 kJ

During the boiling of a liquid, which of the following thermodynamic changes take place?

1. An increase in entropy

2. A decrease in entropy

3. An increase in heat of vaporization

4. An increase in free energy

During a thermodynamic process, a gas inside a cylinder is compressed, requiring 462 Joules of work to be done on the system. Throughout this compression, 128 Joules of heat energy is released into the surroundings. What is the net change in the internal energy (\(\Delta U\)) of the gas?

1. +590 J

2. –334 J

3. +334 J

4. –590 J

For a carnot engine, the source is at 500 K and the sink at 300 K. What is efficiency of this engine

(1) 0.2

(2) 0.4

(3) 0.6

(4) 0.3

From Kirchhoff's equation which factor affects the heat of reaction [MP PMT 1990]

1. Pressure

2. Temperature

3. Volume

4. Molecularity

The absolute enthalphy of neutralisation of the reaction $MgO\left(s\right)+2HCl\left(aq\right)\to MgC{l}_2\left(aq\right)+H_{2}O\left(l\right)$ will be [CBSE PMT 2005]

(1) Less than –57.33 kJ mol^–1

(2) –57.33 kJ mol^–1

(3) Greater than –57.33 kJ mol^–1

(4) 57.33 kJ mol^–1

The heat of transition (ΔH_t) of graphite into diamond would be, where

$C\left(\text{graphite}\right)+O_2\left(g\right)\to C{O}_2\left(g\right);\Delta H=xkJ$

$C\left(\text{diamond}\right)+O_2\left(g\right)\to C{O}_2\left(g\right);\Delta H=ykJ$ [Pb. PET 1985]

(1) $(x+y)kJmo{l}^{-1}$

(2) $(x-y)kJmo{l}^{-1}$

(3) $(y-x)kJmo{l}^{-1}$

(4) None of these

Given that
\(\small {2C(s) + 2O_2(g) \rightarrow 2CO_2(g); \Delta H = -787 kJ}\\ \small{ H_2(g) + {1 \over 2}O_2(g) \rightarrow H_2O(l) ; \Delta H = -286 kJ}\\ \small { C_2H_2(g) + 2 { 1 \over 2}O_2 (g) \rightarrow 2CO_2 (g) + H_2O (l) ; \Delta H= -1301 kJ}\)

The heat of the formation of acetylene is:
1. –1802 kJ

2. +1802 kJ

3. –800 kJ

4. +228 kJ