Element X with atomic number 12 and Y atomic number 17 reacts with hydrogen to form hydrides. Which of them is expected to have a high melting point?
The element with atomic number 12 is Magnesium (Mg) and element with atomic number 17 is Chlorine (Cl).
When Mg reacts with hydrogen it forms MgH2 and chlorine forms HCl. MgH2 is solid and HCl is liquid so MgH2 has a higher melting point.