MCQ
Atoms of two elements P and Q have 5 electrons in 2nd shell and 3rd shell respectively. What will be the atomic numbers of these elements?
- A4 : 15
- B5 : 15
- C7 : 13
- D7 : 15
✓
Answer
- 7 : 15
Explanation:
P has 5 electrons in the second shell (n = 2), thus the electronic configuration is: 2, 5 and atomic no. = 7
Q has 5 electrons in the third shell (n = 3), thus the electronic configuration is: 2, 8, 5 and atomic no. = 15.
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