Question

Which property from following is NOT exhibited by interstitial compounds?

• A. Their melting points are higher than pure metal.
• B. Their densities are less than parent metal.
• C. Their chemical properties are different than parent metal.
• D. These are hard and good conductors of heat and electricity.

Hint:

Interstitial compounds like TiC, WC are extremely hard and have high melting points. Their densities are typically greater than the pure metal.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
Interstitial compounds are formed when small atoms (H, C, N, B) occupy interstitial sites in metal lattices. We need the property that is NOT characteristic of such compounds.

Step 2: Key Formula or Approach:
Recall typical properties: high melting points, extreme hardness, good electrical and thermal conductivity, chemical inertness, and generally higher density than the parent metal.

Step 3: Detailed Explanation:
- (A) True: Interstitial compounds have stronger bonding, so melting points are higher. - (B) False: Densities of interstitial compounds are usually higher than the parent metal because the added mass outweighs the slight lattice expansion. - (C) True: They are chemically more inert compared to the pure metal. - (D) True: They retain metallic conductivity and are very hard.
Thus, the statement about lower density is NOT exhibited.

Step 4: Final Answer:
Option (B) is correct.