Question

Three elements Q, R and T have mass number 40. Their atoms contain 22, 21 and 20 neutrons respectively. Represent their atomic composition with appropriate symbol. ​

Answer 1

The elements are Argon, Potassium and Calcium

Explanation:

Step 1 of 4

The number of protons can be calculated from the formula of mass number

Mass number  = protons + neutrons

Given the number of neutrons

Q = 22

R = 21

T = 20

Step 2 of 4

Number of protons = Mass number - number of neutrons

Number of protons for Q = 40-22 = 18

Number of protons for R = 40-21 = 19

Number of protons for T = 40-20 = 20

Step 3 of 4

Atomic configuration of

$Q_{40} ^{18}$

$R^{19} _{40}$

$T^{20} _{40}$

Step 4 of 4

Now to identify the elements, find elements with atomic numbers 18, 19 and 20

$Ar_{40} ^{18}$

$K_{40} ^{19}$

$Ca_{40} ^{20}$

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