Question

Which from following is the general formula of compound obtained when lanthanoid (Ln) reacts with carbon at elevated temperature?

• A. LnC
• B. \(\mathrm{LnC}_{2}\)
• C. \(\mathrm{Ln}_{3}\mathrm{C}\)
• D. \(\mathrm{LnC}_{3}\)

Hint:

Lanthanoids react with carbon at high temperature to give a carbide of a fixed type.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept
Lanthanoids are reactive metals. At high temperature they combine with many non-metals such as carbon, nitrogen and sulphur.

Step 2: Recall the Reaction
On heating with carbon at about 2773 K, lanthanoids form carbides of the type \(\text{Ln}_3\text{C}\), \(\text{Ln}_2\text{C}_3\) and \(\text{LnC}_2\).
The general carbide quoted for the lanthanoid series is \(\text{LnC}_2\).

Step 3: Compare the options
Among the options, only \(\text{LnC}_2\) is the general formula.

Final Answer:
The lanthanoid carbide has the general formula LnC2. \[ \boxed{\text{(B) }\text{LnC}_{2}} \]