Please refer to Chapter 3 Atoms And Molecules MCQ Class 9 Science with answers below. These multiple-choice questions have been prepared based on the latest NCERT book for Class 9 Science. Students should refer to MCQ Questions for Class 9 Science with Answers to score more marks in Grade 9 Science exams. Students should read the chapter Atoms And Molecules and then attempt the following objective questions.

MCQ Questions Class 9 Science Chapter 3 Atoms And Molecules

The Atoms And Molecules MCQ Class 9 Science provided below covers all important topics given in this chapter. These MCQs will help you to properly prepare for exams.

Question. What is the number of moles present in 62 g of P₄ molecules?
a. 0.25 moles
b. 0.5 moles
c. 1 mole
d. 2 moles

Question. What mass of calcium contains the same number of atoms as present in 2.3 g of sodium?
a. 40 g
b. 13.8 g
c. 9.2 g
d. 4 g

Question. Barium chloride reacts with sulphuric acid according to the following reaction:
                 BaCl₂ + H₂SO₄ → BaSO₄ + 2HCl
The masses of BaCl₂ and H₂SO₄ solutions used were 6.3 g and 8.7 g respectively. If the mass of HCl formed was 5.8g, what would be the mass of BaSO₄ formed?
a. 9.2 g
b. 10.2 g
c. 10.8 g
d. 11.2 g

Question. Calcium carbonate on heating forms calcium oxide and carbon dioxide. If 25 g of CaCO₃ on heating formed 14 g of CaO, calculate the amount of CO₂ that escaped into the air.
a. 22 g
b. 14 g
c. 11 g
d. 5.5 g

Question. What is the mass of 3.011 × 10²³ atoms of hydrogen?
a. 2 g
b. 1 g
c. 0.5 g
d. 0.25 g

Question. Calculate the mass of 0.25 moles of Cl₂ gas.
a. 284 g
b. 71 g
c. 35.5 g
d. 17.75 g

Question. What is the Latin name for sodium?
a. Ferrum
b. Kalium
c. Cuprum
d. Natrium

Question. One atomic mass unit is equal to
a. 1/16th of the mass of an O-16 atom.
b. 1/17th of the mass of an O-17 atom.
c. 1/12th of the mass of a C-12 atom.
d. 1/13th of the mass of a C-13 atom.

Question. The ion is a monoatomic ion.
a. sulphate
b. ammonium
c. calcium
d. carbonate

Question. Which of the following is a polyatomic ion?
a. Sulphide
b. Chloride
c. Nitride
d. Nitrate

Question. 1.08 g of a sample of a compound of nitrogen and oxygen on analysis gave 0.28 g of nitrogen and 0.80 g of oxygen. What is the percentage of nitrogen present in this compound?
a. 74.07 %
b. 35 %
c. 25.93 %
d. 15 %

Question. What is the value of Avogadro’s constant?
a. 1.66 × 10^–24
b. 9.1 × 10^–31
c. 6.022 × 10²⁰
d. 6.022 × 10²³

Question. The ratio by mass of hydrogen and chlorine in hydrogen chloride is
a. 3 : 35.5.
b. 35.5 : 3.
c. 1 : 35.5.
d. 35.5 : 1.

Question. Hydrazine is a compound of nitrogen and hydrogen. The ratio by mass of nitrogen and hydrogen in this compound is 7 : 1. If the mass of hydrogen in hydrazine is 4 g, what is the mass of nitrogen?
a. 7 g
b. 11 g
c. 28 g
d. 56 g

Question. According to the , during a chemical reaction, mass can neither be created nor be destroyed.
a. law of conservation of mass
b. law of constant proportions
c. law of multiple proportions
d. law of combining volumes

Question. The ratio of hydrogen and oxygen in a sample of water collected from a well was found to be 1 : 8 by mass. When a sample of water was collected from a pond and analysed, the ratio of hydrogen and oxygen in it was also found to be 1 : 8 by mass. This data is in accordance with the
a. law of conservation of mass.
b. law of constant proportions.
c. law of multiple proportions.
d. law of combining volumes.

Question. What is the chemical formula of magnesium phosphate?
a. Mg₂(PO₄)₃
b. Mg₃(PO₄)₂
c. Mg₃(PO₄)
d. Mg(PO₄)₂

Question. The chemical compound of sodium hydrogen carbonate is
a. NaHCO₃.
b. Na₂HCO₃.
c. NaCO₃.
d. Na₂CO₃.

Question. Name the smallest particle of an element or a compound which can exist independently and shows the properties of that substance.
a. Atom
b. Molecule
c. Anion
d. Cation

Question. What is the atomicity of a phosphorus molecule?
a. Two
b. Three
c. Four
d. Eight

Question. Which of the following compounds has the chemical formula ZnSO₃?
a. Zinc sulphite
b. Zinc sulphide
c. Zinc sulphate
d. Zinc hydrogen sulphate 

Question. Calculate the mass percentage of carbon in methane (CH₄).
a. 75 %
b. 33.3 %
c. 25 %
d. 20 %

Question. What is the number of atoms of oxygen present in 0.5 moles of O₂?
a. 6.022 × 10²³
b. 3.011 × 10²³
c. 6.022 × 10²⁰
d. 3.011 × 10²⁰

Question. mole(s) of Br₂ contain 6.022 × 10²³ atoms of bromine.
a. 2
b. 1
c. 0.5
d. 0.25

Question. Which of the following is a monoatomic element?
a. Fluorine
b. Sulphur
c. Argon
d. Ozone

Question. is an ionic compound.
a. CCl₄
b. H₂S
c. N₂O₅
d. K₂SO₄

Question. The chemical formula of ethanol is C₂H₅OH. Calculate its molecular mass.
a. 34 u
b. 38 u
c. 46 u
d. 52 u

Question. Calculate the formula unit mass of MgCl₂.
a. 46 g
b. 59.5 g
c. 83 gd
d. 95 g

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