I NEED HELP ASAP!! plsss help

25) a student takes four samples of a white crystalline solid and places each in a well plate. on top of each sample, she carefully places 20 drops of clear mystery liquids a, b, c and d. her results for each well are: liquid a: the solid dissolves quickly. liquid b: the solid appears unchanged. liquid c: a brownish colored liquid is produced. liquid d: fizzing occurs and the well becomes warmer. in which well does a physical change occur?

I’m doing some practice exam questions for biology, and i’m not sure how to do these 3 parts to the question.

Human genes only differ by less than percent. a. 1 b. 6 c. 11 d. 16