Which is an example of a compound whose individual elements are very dangerious, but when combined make a usef

Question

Which is an example of a compound whose individual elements are very dangerious, but when combined make a useful compound?

table salt

sodium metal

chlorine gas

Answer 1

Of your list ,table salt, NaCl is the only compound.

Na explodes when you put it in water.
Cl2 gas is poisonous to breath.
We need salt on our food and in our body every day. Although you can get too much sodium and get high bood pressure.

Answer 2

The answer is contained in the question. Table salt is sodium chloride, and both sodium (explosive) and chlorine (poisonous) are dangerous.