The electrons present in the valence shell of a noble gas atom can be :

51 The electronic configurations of three elements X, Y and Z are :

X : 2 Y : 2, 8, 7 Z : 2, 8, 2

Which of the following is correct regarding these elements ?

52 Which one of the following property is generally not exhibited by ionic compounds ? 54 The atomic number of an element X is 16. The symbol of ion formed by an atom of this element will be : 55 The number of protons in the nucleus of one atom of an element Y is 5. The symbol of ion formed by an atom of this element will be: