Question

normal rain, which has not been contaminated by pollutants, has what ph? slightly acidic slightly basic

Explanation:

Normal rain (uncontaminated by pollutants) contains dissolved carbon dioxide, which reacts with water to form carbonic acid ($\ce{H2CO3}$). Carbonic acid is a weak acid, so normal rain has a slightly acidic pH (typically around 5.6), making "Slightly acidic" the correct choice. "Slightly basic" is incorrect as rain with dissolved $\ce{CO2}$ is acidic, not basic.

Answer:

Slightly acidic