Chemistry Past Questions and Answers

If 30cm³ of oxygen diffuses through porous plug in 7s, how long will it take 60 cm³ of chlorine to diffuse through the same plug?

200 cm³ of air was passed over heated copper in a syringe several times to produce copper (II) oxide.
When cooled, the final volume of air recorded was 158cm³. Estimate the percentage of oxygen in the air?

On recrystallization, 20g of magnesium tetraoxosuphate (IV) forms 41 g of magnesium tetraoxosulphate (IV) crystals, MgSO₄. yH₂O. The value of y is?
(Mg = 24, S = 32, O = 16, H = 1)

Which of the following gases is the most dangerous pollutant?

A major process involved in the softening of hard water is the?