Pb(NO₃)₂ on heating gives a brown gas which undergoes dimerization on cooling ? Identify the gas.

Write the structures of the following:
i) BrF₃
ii) XeF₄

Or

What happens when:
i) SO₂ gas is passed through an aqueous solution Fe³⁺ salt ?
ii) XeF₄ reacts with SbF₅ ?

Give reasons:
i) SO₂ is reducing while TeO₂ is an oxidizing agent.
ii) Nitrogen does not form pentahalide.
iii) ICl is more reactive than I₂

i) Name the method of refining of nickel
ii) what is the role of cryolite in the extraction of aluminium
iii) what is the role of limestone in the extraction of iron from its oxides ?

The elements of 3d transition series are given as:
Sc Ti V Cr Mn Fe Co Ni Cu Zn

Answer the following:
i) Write the element which shows a maximum number of oxidation states.Give reason.
ii) Which element has the highest m.p?
iii) Which elements shows only +3 oxidation state ?
iv) which element is a strong oxidising agent in +3 oxidation state and why?

How would you account for the following?

(i) NF₃ is an exothermic compound but NCl₃ is not.

(ii) The acidic strength of compounds increases in the order:

PH₃ < H₂S < HCl

(a) Draw the structures of the following molecules:

(i) (HPO₃)₃

(ii) BrF₃

(b) Complete the following chemical equations:

(i) HgCl₂ + PH₃-->

(ii) SO₃ + H₂SO₄ -->

(iii) XeF₄ + H₂O  -->

 OR

(a) What happens when?

(i) Chlorine gas is passed through a hot concentrated solution of NaOH?

(ii) Sulphur dioxide gas is passed through an aqueous solution of a Fe (III) salt?

(b) Answer the following:

(i) What is the basicity of H₃PO₃ and why?

(ii) Why does fluorine not play the role of a central atom in inter-halogen compounds?

(iii) Why do noble gases have very low boiling points?

What is the basicity of H₃PO₃?

759.

Complete the following equations:

(i) P₄ + H₂O →
(ii) XeF₄ + O₂F₂ →

Draw the structures of the following:

(i) XeF₂
(ii) BrF₃