Which of the following has the least melting point ?
Solution
Element B Al Ga In
m.p.(°C) 2076 660 30 157
B have high m.p. due to giant polymeric structure. Ga has exceptionally low melting point due to unusual structure consisting of only discrete Ga2 molecules.
Amphoteric oxide among the following is –
Solution
Down the groupbasic character of oxides increases.
B2O3–Acidic
Al2O3–Amphoteric
Ga2O3–Amphoteric
In2O3–Basic
Tl2O3–Basic
The liquefied metal which expands on solidification is :
Solution
Gallium (Ga) is soft , silvery metal. Its melting point is 30ºC. This metal expands by 3.1% when it solidifies and hence, it should not be stored in glass or metal containers.
Ionisation enthalpy (ΔiH1kJ mol-1) for the elements of Group 13 follows the order.
Thermite is a mixture of iron oxide and Al powder. Alreduces iron oxide to iron giving out enormouns heat.
Fe2O3+2Al→2Fe+Al2O3+ Heat
Thermite is amixture of :
Solution
Thermite is mixture of Fe2O3+Al
In the Hoope’s process of aluminium extraction, the fused materials remain in three different layers. These layers remain separated even in electrolytic reduction, because :
Solution
All the layers have different densities and there fore they remain separated from each other.
