9
lesson pretestMultiple Choice

Pretest

Question 9 • Chemistry

What is the number of valence electrons in cadmium Cd ?

Answer
A
1
B
2
C
10
D
12

Explanation

Cadmium’s electron configuration is [Kr] 4d¹⁰ 5s². Its outermost energy level is the fifth level, which contains the two 5s electrons, so cadmium has 2 valence electrons. The 10 electrons in 4d are in a lower energy level, not the outermost shell.

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