Change set
Pick exam & year, then Go.
Question map
Not attempted
Correct
Incorrect
★
Bookmarked
Loading…
Q24
(CDS-I/2026)
Science & Technology › Basic Science (Physics, Chemistry, Biology)
Which one among the following pairs is not correctly matched?
Result
Your answer:
—
·
Correct:
D
Explanation
The pair Helium : Diatomic gas is incorrectly matched. Helium is a noble gas (Group 18) with a completely filled valence shell (1s²). This stable configuration makes it chemically inert, and it exists naturally as a monoatomic gas (He), not diatomic (He&sub2;).
- Nitrogen: Its electronic configuration is 1s² 2s² 2p³. According to Hund's Rule, the three electrons in the 2p subshell remain unpaired.
- Carbon: It has four valence electrons and typically forms four covalent bonds, making it tetravalent.
- Chlorine: It naturally exists in two stable isotopic forms: Chlorine-35 (approx. 75%) and Chlorine-37 (approx. 25%).
How others answered
Each bar shows the % of students who chose that option.
Green bar = correct answer, blue outline = your choice.
Community Performance
Out of everyone who attempted this question.
33%
got it right
✓ Thank you! We'll review this.