Some Basic Concepts of Chemistry — Prelims Questions

What is the mass of $0.5,\text{mol}$ of nitrogen gas (N$_2$)? (Atomic mass of N = $14,\text{u}$)

Which of the following has the maximum number of molecules?

A compound contains $4.07$ hydrogen, $24.27$ carbon, and $71.65$ chlorine. Its molar mass is $98.96,\text{g/mol}$. What are its empirical and molecular formulas? (Atomic masses: H=1, C=12, Cl=35.5)

What is the molarity of a solution prepared by dissolving $49,\text{g}$ of H$_2$SO$_4$ in $250,\text{mL}$ of water? (Assume the volume of the solution remains $250,\text{mL}$ after dissolution. Atomic masses: H=1, S=32, O=16)

How many significant figures are present in $0.002040,\text{g}$?

When $10,\text{g}$ of CaCO$_3$ is decomposed, $4.4,\text{g}$ of CO$_2$ is produced. The mass of CaO produced is: (Atomic masses: Ca=40, C=12, O=16)

A solution is prepared by mixing $100,\text{mL}$ of $0.2,\text{M}$ HCl with $150,\text{mL}$ of $0.1,\text{M}$ HCl. What is the final molarity of the mixed solution?