Some Basic Concepts of Chemistry

Given that density of solution = 1.25 gmL−1.
29.2% HCl means 29.2 g of HCl in 100 g of the solution
Density of the solution =

Mass‌of‌the‌solution

Volume‌of‌solution

⇒ V =

100

1.25

mL
Now, Molarity of the solution =

Number‌of‌moles‌of‌HCl

Volume‌of‌solution×1000

=

29.2∕36.5

100∕1.25

×1000 = 10 M
Using molarity equation M1V1 = M2V2, we get
10 × V = 0.4 × 200 ⇒ V = 8 mL