Question

The elements which make up water can only be separated by chemical means; therefore, water is: a mixture an element a solution a compound

Answer 1

compound

Answer 2

why

Answer 3

A compound is something whose smallest units (e.g. molecules) are made of more than one element. Water molecules are made of two hydrogen atoms and one oxygen atom, so it's a compound because it contains more than one element.

A mixture refers to a combination of two or more different substances that have not combined chemically with one another, meaning you can separate out the different substances using various techniques.

A solution is a specific type of liquid (sort of) and homogeneous mixture in which you have one thing dissolved in another (e.g. salt dissolved in water). The different parts haven't combined chemically and can be separated (if you boil away the water you're still left with salt).