Some Basic Concepts In Chemistry Mock Tests

2.4 g of magnesium (atomic mass = 24 g/mol) is burnt in excess oxygen. The mass of magnesium oxide formed is:

The number of significant figures in 0.002503 is:

A compound contains 40% carbon, 6.67% hydrogen, and 53.33% oxygen by mass. Its molecular mass is 90 g/mol. What is its molecular formula? (C = 12, H = 1, O = 16)

10 g of CaCO₃ on heating gives 7 g of CaO. The percentage yield of CaO is: (atomic masses: Ca = 40, C = 12, O = 16)

In the reaction N₂ + 3H₂ → 2NH₃, 28 g of N₂ reacts with 6 g of H₂. Which is the limiting reagent? (Atomic mass: N = 14, H = 1)

Which of the following species has the highest electron gain enthalpy?

2.8 g of iron reacts with 2.4 g of sulfur to form FeS. What is the limiting reagent? (Fe = 56 g/mol, S = 32 g/mol)

At constant temperature, if the volume of a gas is halved, the pressure becomes: