Question

1. keith measured the temperature of a pond near his house. before he left for school, the water in the pond was 15°c. when he came home from school, the temperature of the pond was higher than it was in the morning. what happened to the water molecules while he was at school?

a) the molecules got closer together.
b) the molecules started moving faster.
c) the water lost cold molecules.
d) the molecules became larger.

Explanation:

When the temperature of water (a substance) increases, according to the kinetic theory of matter, the molecules of the substance gain kinetic energy and start moving faster. Option a is incorrect because molecules don't get closer (that's for cooling and condensation in general, but here temperature increased). Option c is incorrect as water doesn't lose cold molecules (temperature increase is about kinetic energy of existing molecules). Option d is incorrect as molecules themselves don't become larger, their movement and spacing change. So the correct reasoning leads to option b.

Answer:

b. The molecules started moving faster