Yes, CaS is ionic.
Yes.
They're usually made out of ceramics, porcelain, so they can break if dropped for instance.
Soviet Union
specific heat of lpg
Phosphorus is not an oxide. It is an element.
It is a nonmetal.
We use them to perform tasks
One - the four. None of the trailing 0s are significant digits.
Nitrogen
N2O5 is a molecular compound, not ionic.
All numbers which are not "zero" are classed as significant digits. Therefore in the number 129 there will be three digits which are classed as significant.
america did not join the league
It was the Soviet Union
Sodium and Pottasium are metals reacts violently, and is stored to avoid contact with moisture in the air.
This is the halogens group: F., Cl, Br, I, At.