Question

$35$ drops of a liquid has density $1.2$ g/mL, mass $2.4$ g. Assuming molar mass of liquid $70$, select the correct statements.

• A. Volume of one drop of liquid = $0.057$ mL
• B. Mass of one drop of liquid = $0.068$ g
• C. Number of molecules in one drop of liquid =$5.85\times {10}^{20}$
• D. Number of molecules in 35 drop of liquid =$2.05\times {10}^{22}$

Answer 1

Answer: (A), (B), (C), (D)

The correct options are
A Volume of one drop of liquid = $0.057$ mL
B Mass of one drop of liquid = $0.068$ g
C Number of molecules in one drop of liquid =$5.85\times {10}^{20}$
D Number of molecules in 35 drop of liquid =$2.05\times {10}^{22}$

Mass of 1 drop=$\frac{2.4}{35}=0.068g$

Volume of 1 drop=$\frac{Massofonedrop}{Densityofliquid}=\frac{0.068}{1.2}=0.057ml$

Number of molecules in one drop of liquid=Moles of one drop$\times$ $N_A$=$\frac{0.068}{70}\times 6.023\times {10}^{23}=5.85\times {10}^{20}$

Number of molecules in 35 drops of liquid=Moles of 35 drop$\times$ $N_A$=$\frac{2.4}{70}\times 6.023\times {10}^{23}=2.05\times {10}^{22}$