[" The detection of leakage from LPG Cylinders "],[" is facilitated by the addition of "]

LPG cylinders are very appreciable because

The ferrous ion in a given sample is detected by the formation of a white precipitate on the addition of a potassium ferrocyanide solution to it. The precipitate has the constitutional formula:

The ferrous ion in a given sample is detected by the formation of a white precipitate on the addition of a potassium ferrocyanide solution to it. The precipitate has the constitutional formula:

Removal of stamens from a flower to facilitate cross pollination

If there is a leakage of LPG does it rise up or come down in the atmosphere ?Why?

How do you detect the leakage of gas?