Question

A solution of NaOH has a concentration of 4g/dm3. What is the mass of NaOH contained in 250cm3 of this solution?
a) 40g
b) 20g
c) 1g
d) 2g
(Answer it with its solution)​

Answer 1

Answer:

$mass = density \times vol$

Explanation:

M = 0.004 x 0.00025 kg

= 1 g

Answer 2

Answer:

The mass of $NaOH$ solution measured is $1g$.

Therefore, option c) $1g$ is the correct choice.

Explanation:

Given,

The volume of $NaOH$ solution = $250cm^{3}$

The concentration/density of $NaOH$ solution = $4g/dm^{3}$

Convert $g/dm^{3}$ into $g/cm^{3}$

• $1g/dm^{3}$ = $10^{-3} g/cm^{3}$
• $4g/dm^{3}$ = $4 \times 10^{-3} g/cm^{3}$

The mass of $NaOH$ solution =?

As we know,

• The concentration/density of a substance is the mass per unit volume.
• Concentration = $\frac{Mass}{Volume}$
• Mass = Concentration × volume
• Mass = $4\times 10^{-3}\times 250$ = $1g$.

Hence, the mass of $NaOH$ solution = $1g$.