Which pair of elements belong to the same groups in the periodic - ProProfs Discuss

# Which pair of elements belong to the same groups in the periodic table? The elements A, B, C, D and E have atomic numbers 9, 11 , 17,12, and 13 respectively.

A. A & B
B. B & D
C. A & C
D. D & E

This question is part of Periodic Classification of Elements - Paper I
Asked by Kumarans, Last updated: Feb 16, 2020

#### W. Pratt

Want to learn new things and share my knowledge

W. Pratt, Marketing Analyst, MBA, Lincoln

Answered Feb 26, 2019

The correct answer to this question is C. The elements in the question are as follows based on the periodic table: A=9 (Fluorine or F), B=11 (Sodium or Na), C=17 (Chlorine or Cl), D=12 (Magnesium or Mg), and E=13 (Aluminum or Al).

The modern periodic table is arranged in order of increasing atomic number, or the number of protons in the nucleus of an atom, which defines the element. There is a periodic repetition of the chemical elements as their mass increases, so from the way the table is arranged with similar elements in the same column or group, we can see that A (9, or F) lines up directly above C (17, or Cl), giving us answer C (A&C).

#### John Smith

John Smith

Answered Oct 28, 2016

A & c

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