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

Assertion: Aldehydes and ketones, both react with Tollen’s reagent to form silver mirror.

Reason: Both, aldehydes and ketones contain a carbonyl group.

Some enzymes are named after the reaction, where they are used. What name is given to the class of enzymes which catalyse the oxidation of one substrate with simultaneous reduction of another substrate.

How do enzymes help a substrate to be attacked by the reagent effectively?

Observe the figure given below and answer the questions that follow:

1. Which process is represented in the figure?
2. What is the application of this process?
3. Can the same process occur without applying electric field? Why is the electric field applied?

When 19.5 g of F – CH₂ – COOH (Molar mass = 78 g mol⁻¹), is dissolved in 500 g of water, the depression in freezing point is observed to be 1°C. Calculate the degree of dissociation of F – CH₂ – COOH.

[Given: K_f for water = 1.86 K kg mol⁻¹]

Why is the value of van't Hoff factor for ethanoic acid in benzene close to 0.5?

Why is boiling point of 1 M NaCl solution more than that of 1 M glucose solution?

Assertion: Enzymes are very specific for a particular reaction and for a particular substrate.

Reason: Enzymes are biocatalysts.

Select the most appropriate answer from the options given below:

Calculate Van't Hoff factor for an aqueous solution of K₃ [Fe(CN)₆] if the degree of dissociation (α) is 0.852. What will be boiling point of this solution if its concentration is 1 molal? (Kb = 0.52 K kg/mol)

Give the structures of A, B and C in the following reactions:

What is the reason for the stability of colloidal sols?

Define the following term:

Zeta potential

Define the following terms: Associated colloids

Give reasons for the following observations:

Brownian movement provides stability to the colloidal solution.

Write the structures of main products when benzene diazonium chloride `(C_6H_5N_2^(+)Cl^-)`reacts with the following reagents:

CuCN/KCN

Write the structures of main products when benzene diazonium chloride `(C_6H_5N_2^(+)Cl^-)`reacts with the following reagents:

H₂O

Write the structures of main products when benzene diazonium chloride `(C_6H_5N_2^(+)Cl^-)`reacts with the following reagents:

CH₃CH₂OH

Out of MgCl₂ and AlCl₃, which one is more effective in causing coagulation of negatively charged sol and why?

Write the structures of A, B and C in the following:

Out of BaCl₂ and KCl, which one is more effective in causing coagulation of a negatively charged colloidal Sol? Give reason.