Question

The active mass of 5.6 litres of $O_2$ at STP is

• A. 5.6 / 22.4
• B. 8 / 5.6
• C. 32 / 5.6
• D. 0.25 / 5.6

Answer 1

The correct option is B 8 / 5.6

First and foremost, keeping in mind that at room temperature, Oxygen is a gas.

So, Volume of Oxygen(O2) given = 5.6L.

Finding moles, Moles=Volume/22.4.

Moles= 5.6/22.4=1/4moles.

So, finding mass of O2= moles × Mol. Wt.

Mass( in grams) = 1/4 × 32. We have taken 32 as oxygen is is combined state O2, so 16×2=32.

We get, mass =8 grams. Easy one!!!