Dalton's Atomic Theory — Homi Bhabha Class 9 Chemistry MCQs with Solutions
Free Homi Bhabha Class 9 Chemistry Dalton's Atomic Theory MCQs with step-by-step solutions (8 questions). Part of Atoms, Molecules & Structure. Practise online on Prepizo — no login needed.
▶ Practise Dalton's Atomic Theory online (free)
Questions with solutions
Q1 — Dalton's Atomic Theory · medium · theory
According to Dalton's atomic theory, the smallest particle of matter that takes part in a chemical reaction is the:
A. atom ✓ Correct
B. proton
C. electron
D. molecule
Solution: Dalton proposed that atoms are the smallest indivisible particles taking part in chemical reactions.
Q2 — Dalton's Atomic Theory · medium · theory
According to Dalton, atoms of the same element are:
A. made of molecules
B. identical in mass and properties ✓ Correct
C. divisible into protons
D. always different
Solution: Dalton stated that all atoms of a given element are alike in mass and chemical properties.
Q3 — Dalton's Atomic Theory · hard · theory
Which postulate of Dalton's atomic theory was later found to be incorrect?
A. Matter is made up of atoms
B. Atoms combine in small whole-number ratios
C. Atoms of different elements differ
D. Atoms are indivisible ✓ Correct
Solution: Atoms are actually divisible into protons, neutrons and electrons, so this postulate is wrong.
Q4 — Dalton's Atomic Theory · medium · theory
Dalton's theory explains that atoms combine to form compounds in:
A. random fractional ratios
B. small whole-number ratios ✓ Correct
C. ratios that keep changing
D. a 1:1 ratio only
Solution: Atoms of different elements combine in simple whole-number ratios to form compounds.
Q5 — Dalton's Atomic Theory · hard · theory
The idea that during a chemical reaction atoms are neither created nor destroyed but only rearranged is consistent with:
A. the discovery of isotopes
B. the mole concept
C. the law of constant proportion only
D. the law of conservation of mass ✓ Correct
Solution: Since atoms are merely rearranged, the total mass is conserved.
Q6 — Dalton's Atomic Theory · easy · theory
According to Dalton's atomic theory, atoms are:
A. Indivisible and indestructible ✓ Correct
B. Able to be created and destroyed in reactions
C. Made of protons, neutrons and electrons
D. Identical in mass for every element
Solution: Dalton postulated that atoms are the smallest indivisible particles of matter that cannot be created or destroyed.
Q7 — Dalton's Atomic Theory · medium · theory
Which postulate of Dalton's atomic theory directly explains the law of conservation of mass?
A. Atoms of different elements have different masses
B. Atoms of the same element are identical in mass
C. Atoms combine in small whole-number ratios
D. Atoms are neither created nor destroyed in a chemical reaction ✓ Correct
Solution: Because atoms are only rearranged and are neither created nor destroyed, the total mass before and after a reaction stays the same.
Q8 — Dalton's Atomic Theory · hard · theory
The discovery of which of the following is a direct contradiction of one of Dalton's original postulates?
A. The law of definite proportions
B. Isotopes, which are atoms of the same element with different masses ✓ Correct
C. The law of conservation of mass
D. Elements combining in whole-number ratios
Solution: Dalton stated that all atoms of a given element are identical in mass. Isotopes are atoms of the same element with different masses, contradicting this postulate.