In the extraction of copper, explain the smelting process.

How are silicates classified? Give an example for each type of silicate.

Mention the uses of helium.

Why is there a variation of atomic andionic size as we move from Sc to Zn?

Indicate the types of isomerism exhibited by the following complexes and draw the structures for these isomers.
(i) K[Cr(H₂O)₂ (C₂O₄)₂]
(ii) [Co(en)₃]CI₃
(iii) [Co(NH₃)₅(NO₂)](NO₃)₂
(iv) [Pt (NH₃)(H₂O)CI₂]

What are molecular solids? Explain the types of molecular solids.

Calculate the pH of 0.1 M acetic acid if its ionisation constant Ka = 1.8 x 10^-5.

To 1M solution of AgNO₃, 0.75 F quantity of current is passed. What is the concentration of the electrolyte, AgNO₃ remaining in the solution?

Write the characteristics of catalysts.

Compound A of molecular formula C₇H₈ is treated with chlorine and then with NaOH to get compound B of molecular formula C₇H₈O. B on oxidation by acidified K₂Cr₂O₇ gives compound C of molecular formula C₇H₆O. Compound C on treatment with 50% caustic soda gives the compound B and also D. Find A, B, C and D. Explain the reactions.