At the center of the andromeda galaxy is a source of x-rays that scientists believe is a black hole with times more mass than the sun.

a. 30,000
b. 300,000
c. 3,000,000
d. 30,000,000

An atom of nitrogen had seven protons in its nucleus. how many electrons does it have

Actual age your first developed of age well comparison age refers to absolute age true or false

Grasses--> mice--> cats--> coyotes suppose 10,000 units of energy are available at the level of the grasses. what is the total number of energy units lost by the time energy reaches the coyote?