NO₂ (brown colour gas) exists in equilibrium with N₂O₄ (colourless gas) as given by chemical equation.

$\underset{\left(\mathrm{brown}\right)}{2{\mathrm{NO}}_2} \rightleftharpoons \underset{\left(\mathrm{colourless}\right)}{{\mathrm{N}}_2{\mathrm{O}}_4}$

Mixture is slightly brown due to existence of NO₂. If pressure is increased :

• colour intensity is increased

• colour intensity is decreased

• colour intensity first increases and then decreases

• No change in colour intensity

${\mathrm{\Delta H}}_{\mathrm{f}}^{°}$ (C₂H₄) , ${\mathrm{\Delta H}}_{\mathrm{f}}^{°}$ (C₂H₆) are x₁ and x₂ kcalmol^-1 respectively. Then heat of hydrogenation of C₂H₄ is :

• x₁ + x₂

• x₁ - x₂

• -(x₁ - x₂)

• x₁ + 2x₂

The heat of formation of C₁₂H₂₂O₁₁ (s) , CO₂ (g) and (H₂O) are - 530 , -94.3 and- 68.3 kcalmol^-1 respectively. The amount of C₁₂H₂₂O₁₁ to supply 2700 kcal of energy is :

• 382.70 g

• 832.74 g

• 463.9 g

• 684.0 g

Spontaneous adsorption of gas on solid surface is an exothermic process because :

• $\mathrm{\Delta }$H increases for system

• $\mathrm{\Delta }$S increases for gas

• $\mathrm{\Delta }$S decreases for gas

• $\mathrm{\Delta }$G increases for gas

5.

0.1 M solution of CH₃COOH should be diluted to how many times so that pH is doubled ?

• 4.0 times

• 5.55 x 10⁴ times

• 5.55 x 10⁶ times

• 10^-2 times

If the equilibrium constant of the reaction of weak acid HA with strong base is 10⁹ then pH of 0.l M NaA is :

• 5

• 9

• 7

• 8

For the process ,

X (g) + e^- $\to$ X^- (g) ; $\mathrm{\Delta }$H = x

and X^- (g) $\to$ X (g) + e^- ; $\mathrm{\Delta }$H = y

select correct alternate

• Ionisation energy of x^- (g) is y

• Electron affinity of X (g) is x

• Electron affinity of X (g) is - y

• All of the above

Mass of one atom is 6.66 x 10^-23 g. Its percentage in an hydride is 95.24. Thus , hydride is :

• MH

• MH₂

• MH₃

• MH₄

A 1 L flask contains 32 g O₂ gas at 27C. What mass of O₂ must be released to reduce the pressure in the flask to 12.315 atm?

• 8 g

• 16 g

• 24 g

• 32 g

1 mol of O₂ and x mol of Ne in a 10 L flask at constant temperature exert a pressure of 10 atm. If partial pressure of O₂ is 2 atm , moles of Ne in the mixture is :

• 1

• 2

• 4

• 3