Explanation:
The magnetic needle of a compass lines up with Earth's magnetic poles.
Not only astronomers, but all scientists use the technique of rock dating to determine the age of the universe. From the Big Bang Theory, all the celestial bodies were made at the same time. So, the age of the Earth is just the same with the age of the universe. So, they gather rocks deep down in the crust of the Earth and let it undergo radioactive decay. By determining the amount of radioactive material left and half-life, they could compute the age of the Earth.
Some one already asked this question and you can copy paste and google it but I believe it is c you may want to double check
Harmful to the environment
non bio degradable
harmful chemicals <span />
