How much NaNO_3 must be weighed out to make 50 ml of an aqueous solution containing 70 mg Na^(+)...

The NaNO_(3) weighed out to make 50 mL of an aqueous solution containing 70.0 mg Na^(+) per mL is_________ g. (Rounded off to the nearest integer) [Given : Atomic weight in g mol^(-1)-Na:23,N:14,O:16 ]

How many litres of water must be added to 1 litre of an aqueous solution of and having pH 4.70 to create an aqueous solution having pH 5.70?

How much BaCl_(2) would be needed to make 250 mL of a solution having same eoncentration of Cl^(o+) as the one containing 3.78 g of NaCl per 100 mL .

How much BaCl_(2) (in gm) would be needed to make 250 ml of a solution having the same concentration of Cl^(-) as one containing 1.825 gm HCl per 100 ml? (Ba = 137)

How many moles of Ca(OH)_(2) must be dissolved to produce 250 mL of an aqueous solution of pH 10.65 , assuming completer dissociation ?