Hydrogen form compounds with elements having atomic number 9,11,12 and 17. Write the chemical formulae.

Hydrogen forms compounds with elements having atomic chemical formulas? Compare their chemical behaviour.

The valency of the element having atomic number 9 is

The element with atomic number 9,17,35,53,85 are all

The elements with atomic numbers 9, 17, 35,53, 85 and all