The word itself is English.
Gunpowder is typically considered to be one word.
I went to the store to buy some gunpowder for my cannon.
China in the 9th century
gunpowder
On the first bonfire night I think
Sulphur is a constituent part of gunpowder.
One compound word that starts with gun is gunpowder
The gunpowder came to blow open a cave to get the vase for the athanian treasury.
an ingredient in gunpowder is sulphur
There is no specific collective noun for gunpowder, in which case, you use an appropriate noun suited to the situation a pound of gunpowder, a flask of gunpowder, a box of gunpowder, etc.
No, gunpowder is not magnetic.
Gunpowder can be used to make a bomb. So unless you are licensed to be in possession of gunpowder, owning gunpowder is illegal.