MCQ practice · SSC Chemistry Board questions · Chapter 3: Structure of Matter
How many valence electrons does element Y have?
Think it through first, then pick an option.
- a 1
- b 5
- c 7
- d 17
Answer and explanation
Correct answer: c 7
Y (17) is 2, 8, 7: seven in the last shell, so 7 valence electrons.
Why the other options are wrong
- a 1: 1 fits an element like Na (11); Y (17) is 2, 8, 7.
- b 5: 5 is the last shell of P (15), 2, 8, 5; Y (17) is 2, 8, 7.
- d 17: 17 is Y's atomic number, its total electrons; valence electrons are only those in the last shell.
More board questions on this topic
- How many subshells are there in the N shell of an atom?
- At most how many electrons can the 'K' level hold?
- At most how many electrons can the "M" level hold?
- What is the maximum electron capacity of the 'N' level?
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