Question

All members of group $14$ when heated in oxygen form oxides. Which of the following is the correct trend of oxides?

• A. Dioxides $CO_{2}, SiO_{2}$ and $GeO_{2}$ are acidic while $SnO_{2}$ and $PbO_{2}$ are amphoteric
• B. $CO, GeO, SnO$ and $PbO$ are amphoteric
• C. Monoxides react with haemoglobin to form toxic compounds
• D. All oxides burn with blue flame

Answer 1

Answer: (A)

Being acidic $CO _{2}, SiO _{2}$ and $GeO _{2}$ react only with bases.
$\underset{\text{acid}}{CO _{2}}+ \underset{\text{base}}{2 NaOH} \longrightarrow \underset{\text{salt}}{Na _{2} CO _{3}}+ H _{2} O$
$\underset{\text{acid}}{SiO _{2}} +\underset{\text { base }}{2 NaOH } \longrightarrow \underset{\text{salt}}{Na _{2} SiO _{3}}+ H _{2} O$
$\underset{\text{acid}}{GeO_2} + \underset{\text{base}}{2NaOH} \longrightarrow \underset{\text{salt}}{Na _{2} GeO _{3}}+ H _{2} O$
$SnO _{2}$ and $PbO _{2}$ react with both acids and bases. Thus, amphoteric in nature.
$\underset{\text{acid}}{SnO_2} + \underset{\text{base}}{2NaOH} \longrightarrow \underset{\text{salt}}{Na _{2} SnO _{3}}+ H _{2} O$
$\underset{\text{base}}{SnO_2} + \underset{\text{acid}}{4HCl} \longrightarrow \underset{\text{salt}}{SnCl _{4}}+ 2H _{2} O$
$\underset{\text{acid}}{PbO_2} + \underset{\text{base}}{2NaOH} \longrightarrow \underset{\text{salt}}{Na_2PbO_3}+ H _{2} O$
$\underset{\text{base}}{PbO_2} + \underset{\text{acid}}{4HCl} \longrightarrow \underset{\text{salt}}{PbCl_4}+ 2H _{2} O$
Hence, dioxides $CO _{2}, SiO _{2}$, and $GeO _{2}$ are acidic while $SnO _{2}$ and $PbO _{2}$ are amphoteric.