Who proposed the atomic theory of matter? MCQ with Answer and Explanation

Who proposed the atomic theory of matter?
A. John Dalton
B. Ernest Rutherford
C. J.J. Thomson
D. Democritus
Answer: Option A
Solution (By JKExamLibrary)
While Democritus proposed the philosophical concept of the atom in ancient Greece, John Dalton formulated the first scientifically based atomic theory in 1803. His theory stated that elements are composed of indivisible atoms, atoms of the same element are identical, and compounds form from atoms combining in fixed ratios.

This question belongs to: Science chemistry

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Practice More chemistry Questions

Question #1
The alcohol that is poisonous and can cause blindness is:
A. Methanol
B. Ethanol
C. Isopropyl alcohol
D. Butanol

Correct Answer: Option A


Explanation:
Methanol (CH₃OH) is metabolized to formaldehyde and formic acid, causing optic nerve damage, blindness, or death. Ethanol is used in beverages.

This question belongs to: Science chemistry
Question #2
Ethanol reacts with sodium metal to produce:
A. Oxygen
B. Carbon dioxide
C. Ethane
D. Hydrogen gas

Correct Answer: Option D


Explanation:
2C₂H₅OH + 2Na → 2C₂H₅ONa + H₂↑. Alcohols react with alkali metals to form alkoxides and hydrogen, similar to water but slower.

This question belongs to: Science chemistry
Question #3
Which of the following is a decomposition reaction used in black and white photography?
A. 2AgCl → 2Ag + Cl₂
B. 2H₂O → 2H₂ + O₂
C. 2AgBr → 2Ag + Br₂
D. CaCO₃ → CaO + CO₂

Correct Answer: Option C


Explanation:
Silver bromide (AgBr) decomposes on exposure to light (photochemical decomposition) forming silver and bromine: 2AgBr(s) → 2Ag(s) + Br₂(g). This is used in photographic films to capture images. AgCl also light-sensitive but AgBr is primarily used. Calcium carbonate decomposition is thermal. Water electrolysis is electric decomposition.

This question belongs to: Science chemistry

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