Question

Identify the correct statements from the following :
I) $\ce{Ga_2O_3}$ is an amphoteric oxide.
II) The dimer of aluminium chloride has three $Al-Cl-Al$ bridge bonds,
IIl) Boron is very hard refractory solid of high melting temperature.

• A. I, II only
• B. I, III only
• C. II, III only
• D. I, II, III

Answer 1

Answer: (B)

(I) $Ga _{2} O _{3}$ is an amphoteric oxide is the correct statement as it reacts with acid and base both, as shown below:

Reaction with an acid

$Ga _{2} O _{3}+6 HCl \longrightarrow 2 GaCl _{3}+3 H _{2} O$

Reaction with a base

$Ga _{2} O _{3}+2 NaOH \longrightarrow 2 NaGaO _{2}+ H _{2} O$

(II) The dimer of aluminium chloride has three $Al - Cl - Al$ bridge bond is not the correct statement as structure of $Al _{2} Cl _{6}$ is as follows:



(i.e. has only two $Al - Cl - Al$ bridge bonds)

(III) Boron is very hard refractory solid of high melting temperature is the correct statement as its melting point is $2349 \,K$ and is used as refractory solid.