1. a water molecule consists of one oxygen atom joined to each of two hydrogen atoms by a( a type of bond in which the electrons do not spend equal time with the two atoms involved.

Explanation:

Polar covalent bonds are formed when the electrons are not shared equally.

The unequal sharing of electrons happens when the electronegativities of the atoms that form the bonds are different.

The electronegativity of hydrogen atoms is found to be 2.20 and that of oxygen is 3.44.

So, the electronegativity difference found in a H - O bond is 3.44 - 2.20 = 1.24.

That means that oxygen atoms pull the electrons more strongly than hydrogen atoms, which results in that the electrons spend more time closer to the hydrogen atoms than to the oxygen atoms.

You can read more about polar covalent bonds on this link htps://link.

the mantle

explanation:

earth is divided into three layers: the crust or the outermost layer on which we live; the underlying, middle layer - the mantle - and the core (the innermost layer of earth).