Animals and plants cannot directly use all the nitrogen found in our

The correct answer is - atmosphere.

The nitrogen is the most abundant gas in the Earth's atmosphere by far. It is also crucial for the survival for most of the living organisms, be it plants or animals, as they need it and use it in their functioning.

Weirdly enough, the nitrogen can not actually be used by the animals and the plants directly from the atmosphere. In that way, it is actually damaging to them, and can cause diseases or even death.

The plants use it once it enters the soil, while the animals use either directly through consumption of the plants, or by eating other animals that are consuming plants.

sound moves fastest in solids because the molecules are tightly packed and it allows sound to vibrate