A weather balloon contains equal volumes of helium & hydrogen. If the total volume of the balloon is 9.2 litre

Can someone help me calculate the mass of each gas which will be present in the balloon?

equal volumes of each = (1/2) (9.2 litre) = 4.6 litres each

the standard molar volume of gases at STP is 22.4 litres
(22.4 litres per mole of gas)

so use molar masses to find moles:
Hydrogen:
( 4.6 litres each) (2.016 grams H2 / 22.4 litres) = 0.414 grams of H2

Helium:
( 4.6 litres each) (4.0026 grams H2 / 22.4 litres) = 0.822 grams of He


because you only had 2 sig figs in your initial volume,
you might be expected to round your answers off to
0.414 grams of H2
0.822 grams of He