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

Why does leather get hardened after tanning?

Match the statement given in Column I with the phenomenon given in Column II.

Assertion: An ordinary filter paper impregnated with collodion solution stops the flow of colloidal particles.

Reason: Pore size of the filter paper becomes more than the size of colloidal particle.

Assertion: Colloidal solutions show colligative properties.

Reason: Colloidal particles are large in size.

Assertion: Colloidal solutions do not show brownian motion.

Reason: Brownian motion is responsible for stability of sols.

Assertion: Coagulation power of Al³⁺ is more than Na⁺.

Reason: Greater the valency of the flocculating ion added, greater is its power to cause precipitation (Hardy Schulze rule).

Which of the following are peroxoacids of sulphur?

An amorphous solid “A” burns in air to form a gas “B” which turns lime water milky. The gas is also produced as a by-product during roasting of sulphide ore. This gas decolourises acidified aqueous \[\ce{KMnO4}\] solution and reduces \[\ce{Fe^{3+}}\] to \[\ce{Fe^{2+}}\]. Identify the solid “A” and the gas “B” and write the reactions involved.

Define coagulation.

State the Hardy-Schulze rule.

What is electrophoresis?

Convert the following:

Propan-1-ol to 2-Bromopropanoic acid

Define the following term:

Coagulation

Why a negatively charged sol is obtained when AgNO₃ solution is added to KI solution?

Assertion (A): Acetic acid but not formic acid, can be halogenated in the presence of red P and Cl₂.

Reason (R): Acetic acid is a weaker acid than formic acid.

What type of semiconductor is obtained when silicon is doped with boron? 

Give reasons for the following observations: Addition of alum purifies the water

Write the conditions to maximize the yield of H₂SO₄ by contact process.

What are emulsions?

What are the different types of emulsions? Give one example of each type.