The two main types of chemical bonds are and

They are covalent and ionic

The two main types of chemical bonds are covalent and ionic.

A covalent bond is a chemical bond that involves the sharing of electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs, and the stable balance of attractive and repulsive forces between atoms, when they share electrons, is known as covalent bonding.

Ionic bonding is a type of chemical bond that involves the electrostatic attraction between oppositely charged ions, and is the primary interaction occurring in ionic compounds.

i'd say that the moon rock is about 2.2 billion years old.

the earth is thought to have been formed about 4.6 billion years ago by collisions from a cloud of hydrogen, helium, rock, ice and other materials. these were pulled together by gravity to form objects in and around earth like- asteroids and small early planets called planetesimals.

so, the best possible answer to this question will be option d- to harden materials to form different parts of earth’s layers