Coal gas, coal tar and coke are all products of _____. These are all obtained by heating coal in the_______ of air.

Explanation

To answer the question, we will break it down into steps:

### Step 1: Identify the products
The question asks about coal gas, coal tar, and coke. These are all products derived from coal.

### Step 2: Understand the process of obtaining these products
These products are obtained by a specific method of heating coal.

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