State True or False.
Evolution of gas is not a characteristic of chemical reaction.

Answer

To determine whether the statement "Evolution of gas is not a characteristic of chemical reaction" is true or false, we can analyze the characteristics of chemical reactions.

### Step-by-Step Solution:

1. **Understanding Chemical Reactions**:
- A chemical reaction involves the transformation of reactants into products, which often includes changes in properties and the formation of new substances.

2. **Identifying Characteristics of Chemical Reactions**:
- Common characteristics of chemical reactions include:
- **Evolution of gas**: This is often observed when a reaction produces gaseous products.
- **Formation of new substances**: Chemical reactions typically result in the creation of new compounds.
- **Color change**: Many reactions involve a visible change in color.
- **Temperature change**: Reactions can be exothermic (releasing heat) or endothermic (absorbing heat).
- **State change**: Reactants or products may change their physical state (solid, liquid, gas).

3. **Evaluating the Statement**:
- The statement claims that the evolution of gas is *not* a characteristic of chemical reactions. However, as we have identified, the evolution of gas is indeed one of the key indicators of a chemical reaction.

4. **Conclusion**:
- Since evolution of gas is a recognized characteristic of chemical reactions, the statement is **False**.

### Final Answer:
**False**