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An element X has atomic number 17. Which of the following statements is FALSE?
AX belongs to Group 17
BX belongs to the third period
CX is a metal
DX has valency 1
Answer & Solution
Correct answer: C. X is a metal
1. Atomic number 17 corresponds to chlorine.
2. Its electronic configuration is 2, 8, 7.
3. Seven valence electrons place it in Group 17 of the table.
4. Three electron shells place it in period 3.
5. Group 17 valency equals 8 − 7 = 1.
6. Chlorine is a non-metal, not a metal.
7. So the FALSE statement is the claim that X is a metal.
_Source: Selina Concise Chemistry ICSE Class 10, Ch 1 'Periodic Table' (aplustopper.com extract)_
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