CBSE Class 9 Science - MCQ and Online Tests - Chemistry - Unit 3 - Atoms and Molecules

CBSE Class 9 Science – MCQ and Online Tests – Chemistry – Unit 3 – Atoms and Molecules

Every year CBSE  schools conducts Annual Assessment exams for 6,7,8,9,11th standards. These exams are very competitive to all the students. So our website provides online tests for all the 6,7,8,9,11th standard’s subjects. These tests are also very effective and useful for those who preparing for any competitive exams like Olympiad etc. It can boost their preparation level and confidence level by attempting these chapter wise online tests.

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CBSE Class 9 Science – MCQ and Online Tests – Chemistry – Unit 3 – Atoms and Molecules

Question 1.
Which of the following has maximum number of atom?
(a) 18 g H₂O
(b) 18 g of O₂
(c) 18 g of CO₂
(d) 18 g of CH₄

Answer

Answer: (d) 18 g of CH₄

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Question 2.
Which of the following has maximum number of atoms?
(a) 18 g of H₂O
(b) 18 g of O₂
(c) 18 g of CO₂
(d) 18 g of CO₄

Answer

Answer: (d) 18 g of CO₄

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Question 3.
Which of the following correctly represents 360 g of water?
(i) 2 moles of H₂O
(ii) 20 moles of water
(iii) 6.022 × 10²³ molecules of water
(iv) 1.2044 × 10²⁵ molecules of water
(a) (i)
(b) (i) and (iv)
(c) (ii) and (iii)
(d) (ii) and (iv)

Answer

Answer: (d) (ii) and (iv)

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Question 4.
Which of the following represents 12 u?
(a) Mass of 1 hydrogen atom
(b) Mass of C-12 atom
(c) Mass of 0-16 atom
(d) 1/12th of mass of C-12 atom.

Answer

Answer: (d) 1/12th of mass of C-12 atom.

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Question 5.
Which of the following would weigh the highest?
(a) 0.2 mole of sucrose (C₁₂H₂₂O₁₁)
(b) 2 moles of CO₂
(c) 2 moles of CaCO₃
(d) 10 moles of H₂O

Answer

Answer: (c) 2 moles of CaCO₃

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Question 6.
3.42 g of sucrose are dissolved in 18 g of water in a beaker. The number of oxygen atoms in the solution are
(a) 6.68 × 10²³
(b) 6.09 × 10²²
(c) 6.022 × 10²³
(d) 6.022 × 10²³21

Answer

Answer: (a) 6.68 × 10²³

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Question 7.
Which of the following would weigh the highest?
(a) 0.2 mole of sucrose (C₁₂H₂₂O₁₁)
(b) 2 moles of CO₂
(c) 2 moles of CaCO₃
(d) 10 moles of H₂O

Answer

Answer: (c) 2 moles of CaCO₃

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Question 8.
A change in the physical state can be brought about
(a) only when energy is given to the system
(b) only when energy is taken out from the system
(c) when energy is either given to, or taken out from the system
(d) without any energy change

Answer

Answer: (c) when energy is either given to, or taken out from the system

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Question 9.
The relative molecular mass of Na₂S₂O₃.5H₂O is
(a) 250 amu
(b) 250 g
(c) 248 amu
(d) 248 g

Answer

Answer: (c) 248 amu

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Question 10.
Percentage of calcium in calcium carbonate is
(a) 40
(b) 30
(c) 48
(d) 36

Answer

Answer: (a) 40

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Question 11.
Which has maximum number of molecules?
(a) 1 g of CO₂
(b) 1 g of N₂
(c) 1 g of H₂
(d 1 g of CH₄

Answer

Answer: (c) 1 g of H₂

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Question 12.
What mass of carbon dioxide (CO₂) will contain 3.011 × 10²³ molecules?
(a) 11.0 g
(b) 22.0 g
(c) 4.4 g
(d) 44.0 g

Answer

Answer: (b) 22.0 g

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Question 13.
The value of Avogadro’s constant is:
(a) 6.0 × 10²⁴
(b) 6.01 × 10²²
(c) 6.022 × 10²³
(d) 6.022 × 10^-23

Answer

Answer: (c) 6.022 × 10²³

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Question 14.
How many times an atom of sulphur is heavier than an atom of carbon?
(a) 32 times
(b) 12 times
(c) 8/3 times
(d) 12/32 times

Answer

Answer: (c) 8/3 times

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Question 15.
The number of oxygen atoms in 4.4 g of CO₂ is approx.
(a) 6 × 10²²
(b) 6
(c) 12 × 10²³
(d) 1.2 × 10²³

Answer

Answer: (d) 1.2 × 10²³

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