Question

Identify the correct statements from the following :
I) $\mathrm{Ga}{}_2\mathrm{O}{}_3$ 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) $G{a}_2{O}_3$ is an amphoteric oxide is the correct statement as it reacts with acid and base both, as shown below:

Reaction with an acid

$G{a}_2{O}_3+6HCl⟶2GaC{l}_3+3H_{2}O$

Reaction with a base

$G{a}_2{O}_3+2NaOH⟶2NaGa{O}_2+H_{2}O$

(II) The dimer of aluminium chloride has three $Al-Cl-Al$ bridge bond is not the correct statement as structure of $A{l}_{2}C{l}_6$ 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 $2349K$ and is used as refractory solid.