How many grams of concentrated nitric acid solution should be used to prepare `250 mL` of `2.0 M HNO_(3)`? The concentrated acid is `70% HNO_(3)`:

Options

A. 54.0 conc. `HNO_(3)`
B. 45.0 conc. `HNO_(3)`
C. 90.0 conc. `HNO_(3)`
D. 70.0 conc. `HNO_(3)`

Answer

B

Explanation

`M=(W xx1000)/(M_(w)xx V_("solution")(mL))`
`2=(W xx 1000)/(63xx250)`
`W = 31.5 g`
70% `HNO_(3)` means 70g `HNO_(3)` is present in 100g solution.
`therefore 31.5g HNO_(3)` will be pressent in `(100)/(70)xx31.5`
= 45 g of solution.