Question

137) The atoms have atomic numbers 15, 19,
31 and 37. The decreasing order of their
atomic size is
1) 37 < 19 < 31 < 15
2) 19 > 31 > 37 > 15
3) 37 > 19 > 31 > 15
4) 31 > 37 > 19 > 15
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Answer 1

Answer:

The atomic number of elements are 3, 11, 19, 37, 55.

The electronic configuration of elements will be

3 = 2, 1

11 = 2, 8, 1

19 = 2, 8, 8, 1

37 = 2, 8, 8, 18, 1

55 = 2, 8, 8, 18, 18, 1

The pattern shows that all elements have 1 electron in their outermost valence shell and all these elements belong to alkali metals.

Answer 2

Answer:

1 ) 37 < 19 < 31 < 15 is the right answer