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NTA Abhyas 2020

Exam: NTA Abhyas
Year: 2020
Subject: Chemistry
Chapter: Classification of Elements and Periodicity in Properties

NTA Abhyas 2020 · Chemistry · Classification of Elements and Periodicity in Properties

The atomic masses of Li and K are 7 and 39, respectively. According...

The atomic masses of

Li

and

K

are

7

and

39,

respectively. According to law of triads the atomic mass of

Na

will be

Options

A $23$
B $32$
C $46$
D $64$

Correct answer

A. $23$

Step-by-step solution

Atomic mass of middle element of triad is equal to average of masses of terminal elements.

Li

& & & Na& & &

K

72339\dfrac{7 + 39}{2} = 23

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