Five elements A,B,C,D and E have atomic numbers of 2,3,7,10 and 18 respectively. The elements which belong to the ame period of the periodic table are:

Five elements A,B,C,D and E have atomic numbers of 2,3,7,10 and 18 respectively. The elements which belong to the same period of the periodic table are:

The elements A,B,C,D and E have atomic number 9,11,17,12 and 13 respectively. Which pair of elements belong to the same group?

The elements A, B, C, D and E have atomic number 9, 11, 17, 12 and 13 respectively. Which pair of elements belongs to the same group ?

Which of the given elements A,B,C,D and E with atomic number 2,3,7,10 and 30 respectively belong to the same period ?