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CBSE Class 9  >  Class 9 Test  >  Science New NCERT 2026-27 (New Syllabus)  >  Test: Atomic Foundations of Matter - 1 - Class 9 MCQ

Atomic Foundations of Matter - 1 - Free MCQ Practice Test with solutions,


MCQ Practice Test & Solutions: Test: Atomic Foundations of Matter - 1 (15 Questions)

You can prepare effectively for Class 9 Science Class 9 New NCERT 2026-27 (New Syllabus) with this dedicated MCQ Practice Test (available with solutions) on the important topic of "Test: Atomic Foundations of Matter - 1". These 15 questions have been designed by the experts with the latest curriculum of Class 9 2026, to help you master the concept.

Test Highlights:

  • - Format: Multiple Choice Questions (MCQ)
  • - Duration: 15 minutes
  • - Number of Questions: 15

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Test: Atomic Foundations of Matter - 1 - Question 1
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Who proposed the Law of Conservation of Mass?

Detailed Solution: Question 1

Antoine Lavoisier proposed the Law of Conservation of Mass in 1789. He stated that in every chemical operation, an equal quantity of matter exists both before and after the reaction. He is also known as the Father of Modern Chemistry.

Test: Atomic Foundations of Matter - 1 - Question 2
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In a closed system, when baking soda reacts with vinegar, what happens to the total mass?

Detailed Solution: Question 2

In a closed system, the carbon dioxide gas produced during the reaction is trapped inside (e.g., in a balloon). Since no matter escapes, the total mass before and after the reaction remains exactly the same, verifying the Law of Conservation of Mass.

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Test: Atomic Foundations of Matter - 1 - Question 3
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Water always contains hydrogen and oxygen in which fixed mass ratio?

Detailed Solution: Question 3

According to the Law of Definite Proportions proposed by Joseph Louis Proust, water always contains hydrogen and oxygen in the fixed mass ratio of 1:8, regardless of its source or method of preparation. So 9 g of water always gives 1 g of hydrogen and 8 g of oxygen on decomposition.

Test: Atomic Foundations of Matter - 1 - Question 4
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12 g of carbon reacts with oxygen to form 44 g of carbon dioxide. How much CO₂ is produced when 2.4 g of carbon reacts completely?

Detailed Solution: Question 4

If 12 g of carbon produces 44 g of CO₂, then 1 g of carbon produces 44/12 g of CO₂. Therefore, 2.4 g of carbon produces (44/12) × 2.4 = 3.667 × 2.4 = 8.8 g of CO₂. This is based on the Law of Conservation of Mass.

Test: Atomic Foundations of Matter - 1 - Question 5
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Which postulate of Dalton's Atomic Theory explains why mass is conserved during a chemical reaction?

Detailed Solution: Question 5

Dalton postulated that atoms are indivisible particles which cannot be created or destroyed in a chemical reaction. During a chemical reaction, atoms only rearrange themselves. Since no atoms are created or lost, the total mass remains constant — this directly explains the Law of Conservation of Mass.

Test: Atomic Foundations of Matter - 1 - Question 6
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Joseph Louis Proust proposed the Law of Definite Proportions after observing which compound always had fixed ratios?

Detailed Solution: Question 6

Joseph Louis Proust demonstrated that copper carbonate always contains copper, carbon, and oxygen in the same fixed proportion by mass, regardless of where it was found or how it was prepared. This observation led him to propose the Law of Definite Proportions, also called Proust's Law.

Test: Atomic Foundations of Matter - 1 - Question 7
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46 g of sodium reacts completely with chlorine. Given that NaCl has sodium and chlorine in the mass ratio 23:35.5, how much chlorine is needed?

Detailed Solution: Question 7

Using the Law of Definite Proportions, the mass ratio of Na to Cl in NaCl is 23:35.5. Mass of chlorine required = (35.5 / 23) × 46 = 1.543 × 46 = 71 g. So 71 g of chlorine is needed to react completely with 46 g of sodium.

Test: Atomic Foundations of Matter - 1 - Question 8
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How many electrons does a chloride ion (Cl⁻) contain if chlorine has atomic number 17?

Detailed Solution: Question 8

Chlorine has atomic number 17, meaning a neutral chlorine atom has 17 protons and 17 electrons. When chlorine gains one electron to form the chloride ion (Cl⁻), it now has 17 protons and 17 + 1 = 18 electrons, giving it a net charge of 1−.

Test: Atomic Foundations of Matter - 1 - Question 9
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What type of bond holds the two atoms together in an H₂ molecule?

Detailed Solution: Question 9

Each hydrogen atom has 1 electron in its K-shell and needs 1 more to complete the duplet. Two hydrogen atoms share one electron each, forming a single covalent bond represented as H−H. This is the simplest example of covalent bond formation.

Test: Atomic Foundations of Matter - 1 - Question 10
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Which of the following is the correct IUPAC name for N₂O₅?

Detailed Solution: Question 10

N₂O₅ contains 2 nitrogen atoms and 5 oxygen atoms. Using the prefix rules, 'di' is used for 2 nitrogen atoms and 'pentoxide' for 5 oxygen atoms, giving dinitrogen pentoxide. 'Mono' is never used for the first element, and since the prefix 'penta' ends in 'a' and 'oxide' starts with 'o', the 'a' is dropped, giving 'pentoxide'.

Test: Atomic Foundations of Matter - 1 - Question 11
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When sodium loses one electron to form Na⁺, what does the ion contain?

Detailed Solution: Question 11

A neutral sodium atom has atomic number 11, meaning it has 11 protons and 11 electrons. When it loses 1 electron to form Na⁺, it retains all 11 protons but now has only 10 electrons, giving a net positive charge of 1+.

Test: Atomic Foundations of Matter - 1 - Question 12
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What is the correct chemical formula of aluminium oxide?

Detailed Solution: Question 12

Aluminium (Al³⁺) has charge 3+ and oxide (O²⁻) has charge 2−. Using the criss-cross method, the subscript of Al = 2 (from O's charge) and subscript of O = 3 (from Al's charge), giving Al₂O₃. Verification: 2 × 3+ = 6+ and 3 × 2− = 6−, making the compound electrically neutral.

Test: Atomic Foundations of Matter - 1 - Question 13
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Which of the following ionic compounds is soluble in water but insoluble in kerosene?

Detailed Solution: Question 13

Ionic compounds like copper sulfate (CuSO₄) are soluble in water because water is a polar solvent that can interact with ions. However, they are insoluble in non-polar solvents like kerosene. Covalent compounds like camphor and naphthalene show the opposite behaviour — they dissolve in kerosene but not in water.

Test: Atomic Foundations of Matter - 1 - Question 14
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Why do ionic compounds have high melting and boiling points?

Detailed Solution: Question 14

Ionic compounds exist as three-dimensional crystal lattices with strong electrostatic forces of attraction between oppositely charged ions. A large amount of energy is required to break these strong forces, which is why ionic compounds have very high melting and boiling points compared to covalent compounds.

Test: Atomic Foundations of Matter - 1 - Question 15
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What is the molecular mass of water (H₂O)? (H = 1 u, O = 16 u)

Detailed Solution: Question 15

Molecular mass of H₂O = (atomic mass of H × 2) + (atomic mass of O × 1) = (1 × 2) + (16 × 1) = 2 + 16 = 18 u. The molecular mass is calculated by simply adding the atomic masses of all atoms present in one molecule.

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About this Class 9 Practice Test

This test contains 15 MCQs on Atomic Foundations of Matter - 1 with detailed solutions for each question. It is part of the Science Class 9 New NCERT 2026-27 (New Syllabus) course on EduRev, designed to align with the current Class 9 syllabus. Each solution explains not just the correct answer but also gives you an understanding of the topic — not just to attempt the question but also help you prepare for the exam with practice.

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