Science (English Medium) इयत्ता १२ - CBSE Question Bank Solutions

What happens when gelatin is mixed with gold sol?

Match the items given in Column I and Column II.

The reagent which does not react with both, acetone and benzaldehyde.

Which is the most suitable reagent for the following conversion?

\[\begin{array}{cc}
\phantom{....................}\ce{O}\phantom{.....................................}\ce{O}\phantom{.}\\
\phantom{....................}||\phantom{......................................}||\phantom{.}\\
\phantom{}\ce{CH3 - CH = CH - CH2 - C - CH3 -> CH3 - CH = CH - CH2 - C - OH}\phantom{.}
\end{array}\]

Through which of the following reactions number of carbon atoms can be increased in the chain?

(i) Grignard reaction

(ii) Cannizaro’s reaction

(iii) Aldol condensation

(iv) HVZ reaction

Match the reactions given in Column I with the suitable reagents given in Column II.

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?

Differentiate between the following:

Lyophobic Sol and Lyophilic Sol

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.