Calculate the mas

STP means standard temperature-273.15K and pressure

101.325 kPa.

Given

Volume of oxygen gas=1 cm³

We know that

Volume of oxygen gas at STP= 22.4L

1Litre=10³cm³

22.4L=22.410³cm³

Therefore, volume of oxygen gas =22.410³cm³

We know that 22.4L of O₂ contains 1 mol O₂ at STP.

22.410³cm³ of O₂ =1 mol O₂

Therefore,

1cm³ of O₂ = mol of O₂

I mol of O₂ =32 grams of O₂

mol of O₂ = grams of O₂=1.43grams

1g=mg

The mass of 1 cm³ of oxygen kept at STP=1.43mg.