A hydrocarbon (A) containing 90% carbon and having V.D. 20 reacts with dil. `H_2 SO_4` in the presence of `H_2 SO_4` to give (B). Compound (B) is reduced by `LiAIH_4` to (C) which on heating with `H_2 SO_4` gives (D). Compound (A) can be converted into (D) directly by hydrogenation in the presence of deactivated palladium-calcium carbonate catalyst. Identity the compounds (A) to (D) and explain the reactions involved.

Explanation

To solve the problem step by step, we will identify the compounds (A) to (D) based on the given information and reactions.

### Step 1: Determine the Molecular Formula of Hydrocarbon (A)
Given:
- Hydrocarbon (A) contains 90% carbon by weight.
- Vapor density (VD) = 20.

**Calculating Molecular Weight:**
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