A system is changed from state A to state B by one path and from B to A by another path. If E₁ and E₂ are the corresponding changes in internal energy, then [Pb. PMT 2001]

1. $E_1+E_2=-ve$

2. $E_1+E_2=+ve$

3. $E_1+E_2=0$

4. None of the above

If (i) $C+O_2\to C{O}_2$, (ii) $C+1/2O_2\to CO$, (iii) $CO+1/2O_2\to C{O}_2$, the heats of reaction are Q, –12, –10 respectively. Then Q = [Orissa JEE 2004]

(1) – 2

(2) 2

(3) – 22

(4) – 16

Adsorption of gases on a solid surface is generally exothermic because [IIT JEE (Screening) 2004]

1. Enthalpy is positive

2. Entropy decreases

3. Entropy increases

4. Free energy increase

What is the enthalpy change (in kJ) for the process if two moles of an ideal gas is expanded isothermally and reversibly from 1 litre to 10 litre at 300 K?

1. 11.4 kJ

2. –11.4 kJ

3. 0 kJ

4. 4.8 kJ

When a gas undergoes adiabatic expansion, it gets cooled due to -

1. Loss of energy

2. Fall in pressure

3. Decrease in velocity

4. Increase in energy with work done

In an isobaric process, the ratio of heat supplied to the system (dQ) and work done by the system (dW) for diatomic gas is:

(1) 1 : 1

(2) 7 : 2

(3) 7 : 5

(4) 5 : 7

If for a given substance melting point is T_B and freezing point is T_A, then correct variation shown by graph between entropy change and temperature is [DCE 2001]

(1)

(2)

(3)

(4)

Which of the following thermodynamic quantities is measured as heat in a bomb calorimeter during a reaction?

A Beckmann thermometer is used to measure -

1. High temperature

2. Low temperature

3. Normal temperature

4. All temperatures

The heat liberated when 1.89 g of benzoic acid is burnt in a bomb calorimeter at 25°C increases the temperature of 18.94 kg of water by 0.632°C. If the specific heat of water at 25°C is 0.998 cal/g-deg, the value of the heat combustion of benzoic acid is

(1) 771.1 kcal

(2) 871.2 kcal

(3) 881.1 kcal

(4) 981.1 kcal