Given the reaction:
3 cu +8 hno3 → 3 cu(no3)2 + 2 no + 4 h2o
the total number of grams of cu needed to produce
1.0 mole of cu(no3)2 is
a) 64 b) 32 c) 128 192

option A : 64 g

Explanation:

Data Given:

no. of moles Cu(NO₃)₂ = 10 moles

mass of Cu = ?

Reaction Given:

              3Cu +8HNO₃ → 3Cu(NO₃)₂ + 2NO + 4H₂O

Solution:

First we have to calculate moles of Copper that react and moles of Cu(NO₃)₂ that produce in reaction :

For this look at reaction

               3Cu +8HNO₃ → 3Cu(NO₃)₂ + 2NO + 4H₂O

               3 moles                    3 moles

As 3 moles of Cu react to produce 3 moles of Cu(NO₃)₂

So,

1 mole of Cu (copper) will produce 1 mole of Cu(NO₃)₂

Now find the mass of 1 mole Cu (copper)

For this purpose formula used

           mass in grams = no.of moles x molar mass

molar mass of Cu = 64 g/mol

Put values in above formula

           mass in grams = 1 mol / 64 g/mol

           mass in grams =  64 g

So 64 g of Cu is required to produce 1 mole of Cu(NO₃)₂

option A is correct.