Answer:0.7g of salt.
Explanation:
% concentration by mass =
mass of solute/mass of solution
Solute is the salt
Solution is salt +water
Mass of water = Density of water × volume of water
Mass of water = 1000g/L × 2L
Mass of water = 2000g
Let mass of salt = x
Mass of solution = x+2000
0.035/100 = x/x+2000
0.035(x+2000) = 100x
70= 99.965x
x= 0.7g
Therefore the mass of salt to be added is 0.7g