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in Atomic Structure by (49.4k points)
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A number of electrons, protons, and neutrons in chemical species A, B, C, and D is given below.

Element Electrons Protons Neutrons
A 2 3 4
B 10 9 8
C 8 8 8
D 8 8 10

Now answer the following questions: 

1. What is the mass number of A and B? 

2. What is the atomic number of B? 

3. Which two elements represent a pair of isotopes and why? 

4. What is the valency of element C? Also, justify your answers.

1 Answer

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Best answer

(1) Mass number of A = 3 + 4 = 7 Mass number of B = 9 + 8 = 17 

(2) The atomic number of B = Number of protons = 9

(3) Elements C and D represent a pair of isotopes because their atomic numbers are the same, but mass numbers are different.

(4) Electronic configuration of C(8) = 2, 6 So, its valency is 2.

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