A United States 25-cent coin is made from an alloy of 75% copper by weight and 25% nickel by weight. What are the atomic percentages of Cu and Ni that this material contains? 100 g of the alloy of 75% by weight of Cu and 25% by weight are taken as a base, having:

75g Cu 25g Ni The atomic mass of the elements is:

63.54 g/mol for Cu 58.69 g/mol for Ni Therefore, the number of added molgrams of copper and nickel will be:

(give answer in moles).