Give reason for the following:
Zinc granules are preferred for the laboratory preparation of hydrogen rather than pure zinc.

Explanation

**Step-by-Step Text Solution:**

1. **Surface Area Consideration**: Zinc granules have a larger surface area compared to pure zinc. This increased surface area allows for more effective contact between the zinc and the acid (usually hydrochloric acid or sulfuric acid) used in the reaction to produce hydrogen gas.

2. **Faster Reaction Rate**: Due to the larger surface area, the reaction between zinc granules and the acid occurs more rapidly. This means that hydrogen gas is produced at a faster rate when using zinc granules compared to using pure zinc.

3. **Presence of Impurities**: Zinc granules often contain impurities, such as copper. These impurities can act as catalysts, which further enhance the rate of the reaction. Catalysts are substances that increase the speed of a chemical reaction without being consumed in the process.

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