Methane composes most of the natural gas.
A residue from a gunshot is most likely gun powder, which tells you what kind of bullet was shot and the type of gun that was used to shoot the target/victim/person. Some complications may be that there is more than one gun or weapon which uses that residue, so it may be hard to pinpoint it and the bullet can't really tell you who it is unless there's DNA on the bullet, and the chemicals of the bullet may even destroy evidence.
ANSWER
there are 20 number of atoms in compound
Explanation:
In a formula unit of Mg(OH)2, there are one magnesium ion and two hydroxide ions; or one magnesium, two oxygen, and two hydrogen atoms.
