Not sure how to do any of this. Please help!!!

A sample of the compound prepared in this experiment, weighing .1021g, is dissolved in HNO3 and diluted to a volume of 100mL. A 10mL aliquot of that solution is mixed iwth 10mL 6 M NH3. The [Cu(NH3)4 2+] in the resulting solution is 5.16x10^-3 M.

How many moles of Cu were in the original sample, which had been effectively diluted to a volume of 200mL?
How many grams of Cu were in the sample?
How many grams of Cl were in the sample? How many moles?
What is the formula of the Copper Chloride compound?