D. Salt and water
Explanation:
Acid + Alkali -> Salt + water
Solids, liquids, gases, and plasma are all matter. When all atoms that make up a substance are the same, then that substance is an element. Elements made of only one kind of atom. Because of this, elements are called "pure" substances.
hope this helps :)
8.................................
A covalent bond? Not sure how much detail you want, sorry
