Which of the following best describes a pair of elements that will form an ionic bond? c and h: hydrogen easily loses electrons, and carbon gains them. li and o: oxygen easily loses electrons, and lithium gains them. p and cl: phosphorus easily loses electrons, and chlorine gains them. ca and br: calcium easily loses electrons, and bromine gains them.

Carbon and hydrogen don't form ionic bonds with each other because they are both non-metals, and they have similar enough electronegativities to form covalent bonds instead.

Lithium and oxygen can form an ionic bond, but its lithium that easily loses electrons, not oxygen because it only has one valence electron instead of six.

Phosphorous and chlorine don't form ionic bonds with each other for the same reason as carbon and hydrogen.

Calcium and bromine do form ionic bonds with each other, and calcium is the element that loses electrons because it only has two valence electrons instead of seven.