The most reactive metal among the following is: MCQ with Answer and Explanation

The most reactive metal among the following is:
A. Gold
B. Potassium
C. Copper
D. Silver
Answer: Option B
Solution (By JKSSB Mock Tests)
Potassium (K) is an alkali metal placed at the very top of the reactivity series. It reacts violently with water and air, requiring storage in kerosene. Gold, silver, and copper are noble or less reactive metals placed at the bottom of the series, often found in the free state.

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Practice More chemistry Questions

Question #1
Methane on complete combustion with excess oxygen yields:
A. CO₂ and H₂
B. CO₂ and H₂O
C. C and H₂O
D. CO and H₂O

Correct Answer: Option B


Explanation:
CH₄ + 2O₂ → CO₂ + 2H₂O + heat. Complete combustion of any hydrocarbon with sufficient oxygen always produces carbon dioxide and water. Incomplete combustion due to limited oxygen produces carbon monoxide (CO) and/or soot (carbon particles). Methane is the main component of natural gas and biogas. CO is a poisonous gas. The combustion of alkanes is highly exothermic.

This question belongs to: Science chemistry
Question #2
PVC (polyvinyl chloride) is used for making pipes and insulation because it is:
A. Highly flexible without additives
B. Conductor of electricity
C. A good insulator and chemically resistant
D. Biodegradable

Correct Answer: Option C


Explanation:
PVC is a good electrical insulator, resistant to chemicals, water, and fire (self-extinguishing due to chlorine content), making it suitable for cable insulation, pipes, and medical tubing. It is not biodegradable. Flexibility is achieved by adding plasticizers, otherwise rigid. It is an addition polymer of vinyl chloride. Unplasticized PVC (uPVC) is used in construction.

This question belongs to: Science chemistry
Question #3
Which of the following represents a chemical change?
A. Dissolving sugar in water
B. Rusting of iron
C. Sublimation of iodine
D. Melting of ice

Correct Answer: Option B


Explanation:
Rusting is a chemical change because iron reacts with atmospheric oxygen and moisture to form hydrated iron(III) oxide. This new compound possesses entirely different chemical properties from the original iron. The process involves the formation of new chemical bonds and cannot be easily reversed by simple physical methods.

This question belongs to: Science chemistry