NEET Chemistry Some Basic Concepts in Chemistry MCQs

A mixture of $CaCO_3$ and $MgCO_3$ weighing 1.84 g on heating leaves a residue weighing 0.96 g. If the percentage by mass of $CaCO_3$ in the original mixture is x%, what is the value of x/2?

A 20 L vessel contains 0.1 mole of $O_2$ at 300 K. $O_3$ is prepared in the vessel by subjecting $O_2$ to silent electric discharge till the volume is reduced to 15 L at 300K. What is the number of moles of $O_3$ formed?

Equal masses of oxygen and ozone are present in a container at 298 K. The ratio of their partial pressures ($P_{O_2} : P_{O_3}$) is:

A compound contains 28% nitrogen and 72% of a metal by weight. Three atoms of metal combine with two atoms of nitrogen. If the atomic weight of nitrogen is 14, the atomic weight of the metal is:

Two organic compounds X and Y have the same empirical formula $CH_2O$. Compound X has a molar mass of 30 g/mol while compound Y has a molar mass of 90 g/mol. If 0.3 moles of X contains the same number of oxygen atoms as 'm' grams of Y, what is the value of 'm'?

A mixture of $KClO_3$ and $KCl$ weighing 4.96 g was heated to produce $O_2$. The evolved oxygen occupied 448 mL at STP. What percent of the original mixture was $KClO_3$?

A mixture of $CO_2$ and $N_2$ gases contains 0.44 g of $CO_2$ and 0.56 g of $N_2$. The total number of moles of gases in the mixture is:

What is the mass of 0.2 moles of oxygen atoms?

How many molecules are present in 9 g of water?

2.24 L of a gas at STP weighs 3.2 g. The molecular weight of the gas is: