Science (English Medium) Class 12 - CBSE Question Bank Solutions for Chemistry

In the preparation of \[\ce{H2SO4}\] by Contact Process, why is \[\ce{SO3}\] not absorbed directly in water to form \[\ce{H2SO4}\]?

Write the structure of pyrophosphoric acid.

Match the formulas of oxides given in Column I with the type of oxide given in Column II and mark the correct option.

Assertion: \[\ce{SF6}\] cannot be hydrolysed but \[\ce{SF4}\] can be.

Reason: Six \[\ce{F}\] atoms in \[\ce{SF6}\] prevent the attack of \[\ce{H2O}\] on sulphur atom of \[\ce{SF6}\].

Which of the following compound will not undergo azo coupling reaction with benzene diazonium chloride?

The product of the following reaction is:

(i) 

(ii) 

(iii)

(iv)

Which of the following reactions belong to electrophilic aromatic substitution?

(i) Bromination of acetanilide

(ii) Coupling reaction of aryldiazonium salts

(iii) Diazotisation of aniline

(iv) Acylation of aniline

Under what reaction conditions (acidic/basic), the coupling reaction of aryldiazonium chloride with aniline is carried out?

Write the equations for the following reaction:

Salicylic acid is treated with acetic anhydride in the presence of conc H₂SO₄

When benzene diazonium chloride reacts with phenol, it forms a dye. This reaction is called ______.

Define van’t Hoff factor.

What are lyophilic and lyophobic colloids ? Which of these sols can be easily coagulated on the addition of small amounts of electrolytes?

What happens when: SO₂ gas is passed through an aqueous solution Fe⁺³ salt?

Write the major products(s) in the following:

Define the following terms: Lyophilic colloid

Write a method by which lyophobic colloids can be coagulated.

Out of sulphur sol and proteins, which one form multimolecular colloids?

Why vitamin C cannot be stored in our body?

3.9 g of benzoic acid dissolved in 49 g of benzene shows a depression in freezing point of 1.62 K. Calculate the van't Hoff factor and predict the nature of solute (associated or dissociated).

(Given : Molar mass of benzoic acid = 122 g mol⁻¹, K_f for benzene = 4.9 K kg mol⁻¹)

Give reasons for the following observations: Lyophilic sol is more stable than lyophobic sol.