Question

Given below are two statements: Statement I: Animal skin is positively charged and tannin is negatively charged. Statement II: In leather tanning, chromium salts are used in place of tannin.

• A. Both Statements I and II are correct
• B. Both Statements I and II are not correct
• C. Statement I is correct but Statement II is not correct
• D. Statement I is not correct but Statement II is correct

Hint:

Leather tanning is a classic example of mutual coagulation of oppositely charged colloids. Animal Skin (+) Tannin (-) Modern industry often replaces tannin with chromium salts.

Answer 1

The Correct Option is A

Step 1: Understand the topic.
Leather tanning is an everyday use of colloid chemistry. It works because particles with opposite charges pull towards each other.

Step 2: Look at the charge on animal skin.
Animal skin is made of protein. Under tanning conditions this protein behaves as a positively charged colloid.

Step 3: Look at the charge on tannin.
Tannin comes from plants and behaves as a negatively charged colloid.

Step 4: Judge Statement I.
Since skin is positive and tannin is negative, Statement I is correct. The opposite charges let tannin stick to the skin and turn it into leather.

Step 5: Judge Statement II.
Modern industry also uses chromium salts in place of tannin to tan leather. This gives a tougher, better leather, so Statement II is also correct.

Step 6: Combine the judgements.
Both Statement I and Statement II are true.

Step 7: State the final answer.
The correct choice is:
\[ \boxed{\text{Both Statements I and II are correct}} \]