Precipitation reactions occur (1 Point) when group 1 cations are mixed with group 17 anions. when insoluble reactants are mixed. when ionic compounds react to form non-ionic products. predominantly with halide salts. when soluble ionic reactants combine to form insoluble products.

when soluble ionic reactants combine to form insoluble products.

Explanation:

Precipitation reactions are those reactions in which two soluble substances which are ionic in nature combine together forming insoluble salt. This insoluble salts is called precipitate and the reaction is called precipitation reaction. Precipitate is solid substance which is deposited at the bottom of the solution as insoluble material. This precipitate mostly formed in double replacement reaction.

Half-life decay reaction is a first order reaction which uses the formula : t 1/2 = ln 2 / k where k is the decay constant and t 1/2 is the half-life of the material. ln 2 comes from the division of the material into half. k from literature is equal to 0.1551×10−9 yr−1. substituting, t1/2 = 4.468×109 years.