Ncert Exercises & Solutions

(a)Classify following oxides as neutral, acidic, basic or amphoteric:

CO, $B_{2} O_{3}, S i O_{2}, A I_{2} O_{3}, P b O_{2}, T I_{2} O_{3}$

(b)Write suitable chemical equations to show their nature.

(1) CO = Neutral

(2) $B_{2} O_{3}$ = Acidic
Being acidic, it reacts with bases to form salts. It reacts with NaOH to form sodium
metaborate.

$B_{2} O_{3} + 2 N a O H \to 2 N a B O_{2} + H_{2} O$

(3) $S i O_{2}$ = Acidic
Being acidic, it reacts with bases to form salts. It reacts with NaOH to form sodium silicate.

$S i O_{2} + 2 N a O H \to 2 N a_{2} S i O_{3} + H_{2} O$

(4) $C O_{2}$ = Acidic
Being acidic, it reacts with bases to form salts. It reacts with NaOH to form sodium
carbonate.

$C O_{2} + 2 N a O H \to N a_{2} C O_{3} + H_{2} O$

(5) $A I_{2} O_{3}$ = Amphoteric
Amphoteric substances react with both acids and bases. Al2O3 reacts with both NaOH
and $H_{2} S O_{4}$ .

$A I_{2} O_{3} + 2 N a O H \to N a A I O_{2}$
$A I_{2} O_{3} + 3 H_{2} S O_{4} \to A I_{2} (S O$ ₄)3+3H2O

(6) $P b O_{2}$ = Amphoteric
Amphoteric substances react with both acids and bases. $P b O_{2}$ reacts with both NaOH and
$H_{2} S O_{4}$ .

$P b O_{2} + 2 N a O H \to N a_{2} P b O_{3} + H_{2} O$
$2 P b O_{2} + 2 H_{2} S O_{4} \to 2 P b S O_{4} + 2 H_{2} O + O_{2}$

(7) $T I_{2} O_{3}$ = Basic Being basic, it reacts with acids to form salts. It reacts with HCl to form thallium chloride.

$T I_{2} O_{3} + 6 H C I \to 2 T I C I_{3} + 3 H_{2} O$