The reaction 2H₂O → 2H₂ + O₂ is a: MCQ with Answer and Explanation

The reaction 2H₂O → 2H₂ + O₂ is a:
A. Decomposition reaction
B. Displacement reaction
C. Double displacement reaction
D. Combination reaction
Answer: Option A
Solution (By JKExamLibrary)
Water breaks down into hydrogen and oxygen when electricity is passed (electrolysis). A single reactant yields two or more products, hence decomposition. It is also a redox reaction. Combination is the opposite; displacement involves replacing an ion.

Discuss this Question (0)

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

Practice More chemistry Questions

Question #1
Which of the following compounds contains both ionic and covalent bonds?
A. AlCl3
B. NH4Cl
C. K2O
D. MgCl2

Correct Answer: Option B


Explanation:
Ammonium chloride (NH4Cl) consists of the ammonium ion (NH4+) and the chloride ion (Cl-). The bond between NH4+ and Cl- is ionic. However, within the ammonium ion itself, the nitrogen atom is bonded to four hydrogen atoms via covalent bonds (three normal and one coordinate). Thus, it contains both.

This question belongs to: Science chemistry
Question #2
Which allotrope of carbon is a good conductor of electricity?
A. Graphite
B. Charcoal
C. Diamond
D. Buckminsterfullerene

Correct Answer: Option A


Explanation:
Graphite conducts electricity due to delocalized electrons within its layers. Diamond is an insulator. Buckminsterfullerene (C₆₀) is a semiconductor but not as good a conductor as graphite in bulk; fullerene solids can be doped to become conductors. Charcoal is a poor conductor. Graphite electrodes are used in batteries and electrolysis.

This question belongs to: Science chemistry
Question #3
Ethene undergoes which type of reaction with bromine water?
A. Addition
B. Substitution
C. Oxidation
D. Dehydration

Correct Answer: Option A


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