With 21 g of Zinc, and 7 g of CuCl2, how much ZnCl2 is made in grams?

7.07 grams

Explanation:

To calculate the moles :

According to stoichiometry :

1 mole of require 1 mole of

Thus 0.052 moles of will require=  of

Thus is the limiting reagent as it limits the formation of product and is the excess reagent.

As 1 mole of give = 1 mole of

Thus 0.052 moles of give =  of

Mass of

Thus 7.07 g of will be produced from the given masses of both reactants.

a is the correct answer