Answer:
Formation of a solid indicates a chemical reaction occurred.
True
Explanation:
A chemical reaction is said to have occurred when a new substance(s) is (are) formed.
When we mix the sodium nitrate and sodium chloride, the following chemical reaction occurs;
2AgNO3(aq) + 2NaCl(aq) ------> 2AgCl(s) + 2NaNO3(aq)
The appearance of a solid shows that a chemical reaction has occurred and that NaCl really reacted chemically with AgNO3.