In which form is `ZnO` subjected to smelting in records made of clay ?

Explanation

To determine the form in which ZnO is subjected to smelting in clay records, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding ZnO**: Zinc oxide (ZnO) is a compound that is often involved in metallurgical processes, particularly in the extraction of zinc.

2. **Smelting Process**: Smelting is a process that involves the extraction of a metal from its ore by using heat and a chemical reducing agent.

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