Answer:-
7.03 g
Explanation:-
Let the mass of water needed be M.
So total mass = M + 0.37
Now 5% of this solution has 0.37g of rubidium chlorude.
∴ (M +0.37) x (5/100) = 0.37
M +0.37 = 0.37 x 100/5
M + 0.37 = 7.4
M = 7.4-0.37
=7.03
Thus water to be added is 7.03 gram