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

Option (d) is the correct answer.

Explanation:

An ionic bond is formed between a metal and a non-metal as metals have more number of electrons and non-metals are electron deficient in nature.

So, in order to complete their octet metals lose electrons and non-metals gain them.

For example, calcium and bromine will form an ionic bond because being a metal calcium will lose electrons and bromine being a non-metal will gain electrons.

Thus, we can conclude that out of the given options, Ca and Br: Calcium easily loses electrons, and bromine gains them best describes a pair of elements that will form an ionic bond.