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The p-Block Elements

Short Answer Type

771.

Among the hydrides of Group-15 elements, which have the

Lowest boiling point?
Maximum basic character?
Highest bond angle?
Maximum reducing character?

772.
Give reasons:
H₃PO₃undergoes disproportionation reaction but H₃PO₄ does not.

H₃PO₃undergoes disproportionation reaction but H₃PO₄ does not. This is because in H₃PO₃, P is in +3 oxidation state which can get oxidised as well as reduced. Thus, H₃PO₃gives disproportionation, reaction as:

$H_{3} P O_{3} \to H_{3} P O_{4} + P H_{3}$

On the other hand, in H₃PO₄, P is in its maximum oxidation state of +5, which can duly be reduced but not oxidised further. So, H₃PO₄ does not show disproportionation.

773.

Give Reason:

Dioxygen is a gas while Sulphur is a solid at room temperature.

774.

Draw the structures of the following.
(i) XeF₄
(ii) HClO₃

775.

When concentrated sulphuric acid was added to an unknown salt present in a test tube a brown gas (A) was involved. This gas intensified when copper turnings were added to this test tube. On cooling, the gas (A) changed into a colourless solid (B).
(i) Identify (A) and (B)
(ii) Write the structures of (A) and (B)
(iii) Why does gas (A) change to solid on cooling