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

When a liquid boils, there is [JIPMER 2002]

(1) An increase in entropy

(2) A decrease in entropy

(3) An increase in heat of vaporization

(4) An increase in free energy

The work done to contract a gas in a cylinder, is 462 joules. 128 joule energy is evolved in the process. What will be the internal energy change in the process [MP PMT 2003]

(1) + 590 joules

(2) – 334 joules

(3) + 334 joules

(4) – 590 joules

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