Question

2. (i) Hydrogen and oxygen combine (3)
in the ratio of 1:8 by mass to form water.
What mass of oxygen gas would be required to
react completely with 3 g of hydrogen gas?
​

Answer 1

2H2 + O2 = 3H2O

4g. 32g. 36g

Since, 32 g of oxygen reacts with 4g of H2

so 3g H2 will require 3 x 32/4 = 24 g of O2