Recommend an element use to fill bottles that contain ancient paper. the element should be a gas at room temperature, should be denser than helium, and should not easily react with other elements. hurry

Neon is heavier than helium and does not react with other elements. This is because Neon is a noble gas and is very stable because its outer electrons are filled.

Find the volumes  og each  box

Single serving box = 1/2 * 7 *3 * 9 =  94.5  cm^3

Family size = 1/2 * 8 * 3 * 16 = 192 cm^3

Find the cost by unit volume:-  single costs 1.25 /  94.5 = 0.013228 
 family costs 2.5 / 192  0.01302

So the family bar costs less by unit volume  and is the better buy.