Which discovery by astronomer vera rubin prove the existence of dark matter

When observing the Andromeda Galaxy, Vera Rubin discovered the material at the edges of  the spiral-shaped galaxy (like most other galaxies) were moving at the just as fast as those at the center (almost near the black hole). This challenged the Newtonian law of motion.  Therefore there had to be an unseen force that acted on these galaxies (dark matter) and space altogether.

True

Explanation:

The nitrogen fixation is a process that involves conversion of atmospheric nitrogen to nitrates in the soil. This process is mainly performed by nitrogen-fixing bacteria present in the soil.

The nitrogen fixation is important for plants and animals. The nitrogen present in the atmosphere cannot be used directly by animals and plants. The nitrogen is main constituent of chlorophyll that is required for the process of photosynthesis and for amino acids that synthesize proteins. Thus, Nitrogen fixation makes nitrogen gas useful to crops.