JEE MAIN - Chemistry (2022 - 26th July Morning Shift - No. 16)
Chlorophyll extracted from the crushed green leaves was dissolved in water to make $$2 \mathrm{~L}$$ solution of Mg of concentration $$48\, \mathrm{ppm}$$. The number of atoms of $$\mathrm{Mg}$$ in this solution is $$x \times 10^{20}$$ atoms. The value of $$x$$ is ___________. (Nearest Integer)
(Given : Atomic mass of $$\mathrm{Mg}$$ is $$24 \mathrm{~g} \mathrm{~mol}^{-1} ; \mathrm{N}_{\mathrm{A}}=6.02 \times 10^{23} \mathrm{~mol}^{-1}$$ )
Answer
24
Explanation
In $$2 \mathrm{L} \rightarrow 96 \,\mathrm{mg}$$ of $$\mathrm{Mg}$$
Number of atoms of $$\mathrm{Mg}=\frac{96 \times 10^{-3}}{24} \times \mathrm{N}_{\mathrm{A}}$$
$$ \begin{aligned} &=4 \times 10^{-3} \times 6 \times 10^{23} \\ &=24 \times 10^{20} \end{aligned} $$
$$x=24$$
Number of atoms of $$\mathrm{Mg}=\frac{96 \times 10^{-3}}{24} \times \mathrm{N}_{\mathrm{A}}$$
$$ \begin{aligned} &=4 \times 10^{-3} \times 6 \times 10^{23} \\ &=24 \times 10^{20} \end{aligned} $$
$$x=24$$
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