Question

1. Lava is hot liquid rock. When lava flows over solid ground, the solid ground beneath it increases in temperature. What happens to the molecules in the solid ground when the temperature is increasing?

Responses

a
More heat molecules combine with the molecules in the ground.
More heat molecules combine with the molecules in the ground.

b
The cold energy of the molecules in the ground decreases.
The cold energy of the molecules in the ground decreases.

c
The energy of the molecules in the ground decreases.
The energy of the molecules in the ground decreases.

d
The energy of the molecules in the ground increases.

Answer 1

d

When the ground is heated by the lava, heat energy is transferred into the ground so the molecules gain kinetic energy — they vibrate/move faster and collide more frequently. Options a–c are incorrect because "more heat molecules" and "cold energy" are not meaningful and options b/c state the energy decreases, but it actually increases.