Question

Assertion (A): Colloidal solution is electrically neutral. Reason (R): Due to similar nature of the charge carried by the particles, they repel each other and do not combine to form bigger particles.

• A. Both (A) and (R) are true and (R) is the correct explanation of (A)
• B. Both (A) and (R) are true and (R) is not the correct explanation of (A)
• C. (A) is true but (R) is false
• D. Both (A) and (R) are false

Hint:

\textbf{Charge on particles} → stability of colloids
\textbf{Counter-ions in medium} → electrical neutrality of colloidal solution Do not confuse stability with neutrality.

Answer 1

The Correct Option is B

Step 1: Analyse Assertion (A). A colloidal solution as a whole is electrically neutral. Although the colloidal particles carry a charge, this charge is balanced by an equal and opposite charge of counter-ions in the dispersion medium. \[ \Rightarrow \text{Assertion (A) is true.} \]
Step 2: Analyse Reason (R). Colloidal particles usually carry the same type of charge, due to which:
they repel each other,
aggregation is prevented,
the colloidal solution remains stable. \[ \Rightarrow \text{Reason (R) is also true.} \]
Step 3: Check whether (R) explains (A). Reason (R) explains the stability of colloids, not their electrical neutrality. Electrical neutrality is due to the presence of counter-ions, not due to repulsion between similarly charged particles. \[ \Rightarrow \text{(R) is not the correct explanation of (A).} \]
Hence, the correct answer is \[ \boxed{\text{(B) Both (A) and (R) are true but (R) is not the correct explanation of (A)}} \]