In Lassaigne's test, the elements present in the organic compound are converted 'X' to ‘Y’ form by fusion with ‘Z’ metal.Supply the missing terms :

2Na+S⟶Na2 SNa+X (halogen) ⟶NaXNa+C+N⟶NaCNHere, it is very important to note that Li and K cannot be used. because the compounds of lithium are dominatingly covalent and reactivity of K is so high that the organic compound catches fire.