1

JEE Main 2016 (Online) 9th April Morning Slot

For the reaction,
A(g) + B(g) $\to$ C(g) + D(g), $\Delta$Ho and $\Delta$So are, respectively, − 29.8 kJ mol−1 and −0.100 kJ K−1 mol−1 at 298 K. The equilibrium constant for the reaction at 298 K is :
A
1.0 $\times$ 10$-$10
B
1.0 $\times$ 1010
C
10
D
1
2

JEE Main 2016 (Online) 9th April Morning Slot

The plot shows the variation of −$ln$ Kp versus temperature for the two reactions.

M(s) + ${1 \over 2}$ O2(g) $\to$ MO(s) and

C(s) + ${1 \over 2}$ O2(g) $\to$ CO(s)

Identify the correct statement :
A
At T > 1200 K, carbon will reduce MO(s) to M(s).
B
At T < 1200 K, the reaction

MO(s) + C(s) $\to$ M(s) + CO(g) is spontaneous.
C
At T < 1200 K, oxidation of carbon is unfavourable
D
Oxidation of carbon is favourable at all temperatures.
3

JEE Main 2016 (Online) 10th April Morning Slot

A solid XY kept in an evacuated sealed container undergoes decomposition to form a mixture of gases X and Y at temperature T. The equilibrium pressure is 10 bar in this vessel. Kp for this reaction is :
A
5
B
10
C
25
D
100
4

JEE Main 2017 (Offline)

pKa of a weak acid (HA) and pKb of a weak base (BOH) are 3.2 and 3.4, respectively. The pH of their salt (AB) solution is:
A
6.9
B
7.0
C
1.0
D
7.2

Explanation

The salt (AB) given is a salt is of weak acid and weak base. Hence its pH can be calculated by the formula

$\therefore$ pH = 7 + ${1 \over 2}p{K_a} - {1 \over 2}p{K_b}$

= 7 + ${1 \over 2}\left( {3.2} \right) - {1 \over 2}\left( {3.4} \right)$

= 6.9