In which of the following reactions does the heat change represent the heat of the formation of water

1. $2H_2\left(g\right)+O_2\left(g\right)\to 2H_{2}O\left(l\right);\Delta H=-116kcal$

2. $H_2\left(g\right)+\frac{1}{2}{O}_2\left(g\right)\to H_{2}O\left(l\right);\Delta H=-58kcal$

3. $H^{+}(aq.)+O{H}^{-}(aq.)\to 2H_{2}O\left(l\right);\Delta H=-13.7kcal$

4. $C_2{H}_2\left(g\right)+2\frac{1}{2}{O}_2\left(g\right)\to 2C{O}_2\left(g\right)+H_{2}O\left(l\right)$; $\Delta H=-310kcal$

Based on the following thermochemical equations

$H_{2}O\left(g\right)+C\left(s\right)\to CO\left(g\right)+H_2\left(g\right);\Delta H=131kJ$

$CO\left(g\right)+\frac{1}{2}{O}_2\left(g\right)\to C{O}_2\left(g\right);\Delta H=-282kJ$

$H_2\left(g\right)+\frac{1}{2}{O}_2\left(g\right)\to H_{2}O\left(g\right);\Delta H=-242kJ$

$C\left(s\right)+O_2\left(g\right)\to C{O}_2\left(g\right);\Delta H=XkJ$

The value of X is [CBSE PMT 1992]

(1) –393 kJ

(2) –655 kJ

(3) +393 kJ

(4) +655 kJ

If enthalpies of formation of C₂H₄(g), CO₂(g) and H₂O(l) at 25°C and 1 atm pressure be 52, – 394 and –286 kJ mol^–1 respectively, the enthalpy of combustion of C₂H₄(g) will be [CBSE PMT 1995; AIIMS 1998; Pb. PMT 1999]

1. +1412 kJ mol^–1

2. –1412 kJ mol^–1

3. +141.2 kJ mol^–1

4. –141.2 kJ mol^–1

Ozone is prepared by passing silent electric discharge through oxygen. In this reaction [AFMC 1998]

(1) Energy is given out

(2) Energy is absorbed

(3) Oxygen is loaded with energy

(4) Oxygen is dissociated into atoms

Combustion of glucose takes place according to the equation,

${\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6+6{\mathrm{O}}_2\to 6{\mathrm{CO}}_2+6{\mathrm{H}}_2\mathrm{O}$, $∆<mspace\; width="1em"></mspace>H<mspace\; width="1em"></mspace>=<mspace\; width="1em"></mspace>-72<mspace\; width="1em"></mspace>K<mspace\; width="1em"></mspace>cal$

Energy required for the production of 1.6 g of glucose is -

(Molecular mass of glucose = 180 g)

1. 0.064 kcal

2. 0.64 kcal

3. 6.4 kcal

4. 64 kcal

Equal amounts of water are used to dissolve four different compounds at \(25^\circ\text{C}\). Given their respective molar heats of solution (\(\Delta H_{\text{sol}}\)) below, identify which compound will absorb the maximum quantity of heat from the surroundings upon dissolution?

1. \(\text{HNO}_3; (\Delta H = -33\text{ kJ/mol})\)

2. \(\text{KCl} ;(\Delta H = +17.64\text{ kJ/mol})\)

3. \(\text{NH}_4\text{NO}_3; (\Delta H = +25.5\text{ kJ/mol})\)

4. \(\text{HCl} ; (\Delta H = -74.1\text{ kJ/mol})\)

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 a process if two moles of an ideal gas are 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