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 and ionic 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.