Question

4.5 g of compound A (MW = 90) was used to make 250 mL of its aqueous solution. The molarity of the solution in M is x × 10⁻¹. The value of x is ______. (Rounded-off to the nearest integer)

Options

• 1

• 2

• 3

• 4

Answer 1

4.5 g of compound A (MW = 90) was used to make 250 mL of its aqueous solution. The molarity of the solution in M is x × 10⁻¹. The value of x is 2.

Explanation:

Moles of A = `"Weight"/"MW"`

= `4.5/90`

= `1/20`

= 0.05

Volume (Lit) = `250/1000` = 0.250 lit

Molarity (M) = `"Mole"/(("Lit")"volume")`

= `0.05/0.250`

= 0.2

= 2 × 10⁻¹ `"mol"/"Lit"`

x = 2