A compound contains 40% carbon, 6.7% hydrogen and 53.3% oxygen. Its molar mass is 180 g. Find its empirical and molecular formulae.

Calculate the mass of 3.011 × 10²³ molecules of water. (H = 1, O = 16)

How many grams of sodium hydroxide are needed to prepare 250 cm³ of a 0.1 M solution? (Na = 23, O = 16, H = 1)

Distinguish between molarity and molality, and state which is independent of temperature.

Calculate the number of moles in 5.6 g of nitrogen gas. (N = 14)

Calculate the molarity of a solution containing 4 g of sodium hydroxide in 500 cm³ of solution. (Na = 23, O = 16, H = 1)

State the law of conservation of mass and the law of constant proportions.