1

### AIPMT 2011 Mains

Which of the following statements is incorrect?
A
Pure sodium metal dissolves in liquid ammonia to give blue solution.
B
NaOH reacts with glass to give sodium silicate.
C
Aluminium reacts with excess NaOH to give Al(OH)3.
D
NaHCO3 on heating gives Na2CO3.

## Explanation

Al reacts with NaOH to give sodium metaaluminate.

2Al(s) + 2NaOH (aq) + 2H2O(l) $\to$ 2NaAlO2 + 3H2
2

### AIPMT 2011 Prelims

Name the two type of the structure of silicate in which one oxygen atom of [SiO4]4$-$ is shared?
A
Linear chain silicate
B
Sheet silicate
C
Pyrosilicate
D
Three dimensional

## Explanation

Pyrosilicate contains two units of SiO44– joined along a corner containing oxygen atom.
3

### AIPMT 2010 Mains

How many bridging oxygen atoms are present in P4O10?
A
6
B
4
C
2
D
5

## Explanation

4

### AIPMT 2010 Prelims

Oxidation states of P in H4P2O5, H4P2O6, H4P2O7 are respectively
A
+3, +5, +4
B
+5, +3, +4
C
+5, +4, +3
D
+3, +4, +5

## Explanation

The oxidation state can be calculated as :

H4P2O5 : +4 + 2x + 5(– 2) = 0 $\Rightarrow$ 2x – 6 = 0 $\Rightarrow$ x = +3

H4P2O6 : +4 + 2x + 6(– 2) = 0 $\Rightarrow$ 2x – 8 = 0 $\Rightarrow$ x = +4

H4P2O7 : +4 + 2x + 7(– 2) = 0 $\Rightarrow$ 2x – 10 = 0 $\Rightarrow$ 2x = 10 $\Rightarrow$ x = +5