1

### AIPMT 2001

Molarity of liquid HCl, if density of solution is 1.17 g/ce is
A
36.5
B
18.25
C
32.05
D
42.10

## Explanation

Molarity = ${{1.17 \times 1000} \over {36.5 \times 1}} = 32.05$
2

### AIPMT 2000

Oxidation numbers of A, B, C are + 2, +5 and $-$2 respectively. Possible formula of compound is
A
A2(BC2)2
B
A3(BC4)2
C
A2(BC3)2
D
A3(B2C)2

## Explanation

In A3(BC4)2, (+2) $\times$ 3 + 2[+5+4(-2)]

$\Rightarrow$ +6 + 10 -16 = 0

$\therefore$ Oxidation numbers of A, B, C are + 2, +5 and $-$2 respectively.
3

### AIPMT 2000

Volume of CO2 obtained by the complete decomposition of 9.85 g of BaCO3 is
A
2.24 L
B
1.118 L
C
0.84 L
D
0.56 L

## Explanation

BaCO3 $\to$ BaO + CO2

197.34 g $\to$ 22.4 L at N.T.P

9.85 g $\to$ ${{22.4} \over {197.34}} \times 9.85 = 1.118\,L$
4

### AIPMT 2000

In quantitative analysis of second group in laboratory, H2S gas is passed in acidic medium for precipitation. When Cu2+ react with KCN, then for product, true statement is
A
K2[Cu(CN)4] more soluble
B
K2[Cd(CN)4] less stable
C
K2[Cu(CN)2] less stable
D
K2[Cd(CN)3] more stable

## Explanation

K3[Cu(CN)2] = 3(+1)+x+2(-1) = 0

$\Rightarrow$ x = -1

$\therefore$ the oxidation no. of 'Cu' is -1 (-ve), so this complex is unstable so it is not formed.