What do we need to learn about inclined planes

Inclined plane, simple machine consisting of a sloping surface, used for raising heavy bodies. The force required to move an object up the incline is less than the weight being raised, discounting friction. The steeper the slope, or incline, the more nearly the required force approaches the actual weight.

Explanation:

1 a

2 d

3 a

4 c

explanation:

it means there are 3 atoms of oxygen