Which of the following is an element of Group 18? MCQ with Answer and Explanation

Which of the following is an element of Group 18?
A. Oxygen
B. Hydrogen
C. Helium
D. Nitrogen
Answer: Option C
Solution (By JKSSB Mock Tests)
Group 18 elements are noble gases: helium, neon, argon, krypton, xenon, radon. They have completely filled valence shells, making them chemically inert (though xenon can form compounds). Nitrogen is Group 15, Oxygen Group 16, Hydrogen is unique (Group 1).

Discuss this Question (0)

No comments yet. Be the first to start the discussion!

Practice More chemistry Questions

Question #1
According to Boyle's law, at constant temperature, the pressure of a gas is inversely proportional to its:
A. Temperature
B. Mass
C. Density
D. Volume

Correct Answer: Option D


Explanation:
Boyle's law: P ∝ 1/V or PV = constant at constant T and n. So if volume increases, pressure decreases. This is because gas molecules have more space and hit the walls less frequently. An example is a syringe: pulling the plunger increases volume, decreases pressure.

This question belongs to: Science chemistry
Question #2
Ethene undergoes which type of reaction with bromine water?
A. Oxidation
B. Dehydration
C. Addition
D. Substitution

Correct Answer: Option C


Explanation:
Ethene (C₂H₄) adds Br₂ across the double bond to form 1,2-dibromoethane. Bromine water decolorizes, a test for unsaturation. Alkanes undergo substitution.

This question belongs to: Science chemistry
Question #3
Hard water can be softened by adding washing soda because it:
A. Precipitates calcium and magnesium ions as carbonates
B. Removes chlorine
C. Kills bacteria
D. Increases pH

Correct Answer: Option A


Explanation:
Na₂CO₃ reacts with Ca²⁺/Mg²⁺ to form insoluble CaCO₃/MgCO₃, which are removed. This is permanent hardness removal. Boiling works for temporary hardness. Ion exchange is another method.

This question belongs to: Science chemistry