Which of these mixtures would be easiest to separate?
A: Fruit salad

The atmosphere of Mars is almost entirely composed of a greenhouse gas. Compared with Earth, which factor accounts for the low, nighttime surface temperatures on Mars?
A: The atmosphere on Mars has an extremely low density.

Which sentence best describes the organization of the heart?
A: The heart is an organ made up of different types of tissues, each of which has different types of cells.

A student wraps a wire around an iron nail. The student then connects the wire to a battery. The nail attracts another nail and they stick together. What force holds the two nails together?
A:
magnetic force