Question

How many grams of sodium chloride are required to make a 1.0 L solution with a concentration of 3.5 M?

Answer 1

3.5 M has 3.5 moles per litre
so we have one litre, so we need 3.5 moles
moles = mass/molarmass
3.5 * 23 = 80.5

Answer 2

The molecular weight of NaCl is 58.44; sodium =22.99; Chlorine=35.45. 

A 1 molar solution is the molecular weight in grams in 1 litre of water,
So,  a 3.5 molar solution would be = 58.44g * 3.5, 204.54

In short, Your Answer would be 204.54

Hope this helps!