Question

element X, Y and Z have atomic number 6 9 and 12 respectively which one forms and onion​

Answer 1

Element x with 'atomic number' 6 is carbon, y with 9 is fluorine, and z with 12 is magnesium. Magnesium is a metal so it would lose an electron to form an anion. Fluorine a nonmetal will gain an electron to form a cation.