# Multiple Choice Questions for Atoms and Molecules

Given below are the Class 9 Science CBSE Objective type Questions or MCQ for Atoms and Molecules
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## Multiple Choice Questions

Question 1.
Which of the following has largest number of particles?
a. 8g of $CH_4$
b. 4.4g of $CO_2$
c. 34.2g of $C_{12}H_{22}O_{11}$
d.2g of $H_2$

Question 2.
The number of molecules in 16.0g of oxygen is:
a.$6.02 \times 10^{23}$
b.$6.02 \times 10^{-23}$
c.$3.01 \times 10^{-23}$
d.$3.01 \times 10^{23}$

Question 3.
The percentage of hydrogen in $H_{2}O$ is:
a.8.88
b.11.12
c.20.60
d.80.0

Question 4
. Find the mass of oxygen contained in 1 kg of potassium nitrate $KNO_{3}$.
a.475.5g
b.485.5g
c.475.2g
d.485.2g

Question 5.
How many moles of electron weight one kilogram?
a. $6.023 \times 10^{23}$
b. $6.023 \times 10^{8}$
c. $9.108 \times 10^{54}$
d. $1.82 \times 10^{8}$

Question 6.
25.4g of iodine and 14.2g of chlorine are made to react completely to yield a mixture of $ICl$ and $ICl_{3}$. Calculate the ratio of moles of $ICl$ and $ICl_{3}$:
a.1: 1
b.2: 1
c.3: 1
d.1: 2

Question 7.
The mass of sodium in 11.7 g of sodium chloride is:
a.2.3g
b.4.6g
c.6.9g
d.7.1g

Question 8.
The formula of a chloride of a metal M is $MCl_{3}$, the formula of the phosphate of metal M will be:
a.$MPO_{4}$
b.$M_2PO_{4}$
c.$M_{3}PO_{4}$
d.$M_2(PO_{4})_{3}$

Question 9.
Which of the following contains the largest number of molecules?
a.0.2 mol $H_{2}$
b.8.0g $H_{2}$
c.17g of $H_{2 }O$
d.6.0 g of $CO_{2}$

Question 10.
One gram of which of the following contains largest number of oxygen atoms?
a.O
b.$O_{2}$
c.$O_{3}$
d.All contains same

Question 11.
The percentage by weight of $O_{2}$ in $CaO_{4}$ ( O = 16, S = 32, Ca = 40) is:
a.64
b.28.2
c.47.2
d.16.2

Question 12.
The percentage by weight of Zn in white vitriol, $ZnSO_{4}.7H_{2}O$ (Zn = 65, S = 32, O = 16, H = 1) is approximately:
a.23
b.33
c.43
d.13

Question 13.
The formation of $SO_{2}$ and $SO_{3}$ explain:
a.The law of conservation of mass
b.The law of multiple proportions
c.The law of definite properties
d.Boyle's law

Question 14.
The law of definite proportions was given by:
a.John Dalton
b.Humphry davy
c.Proust

Question 15.
Molecular mass is defined as the:
a.Mass of one atom compared with the mass of one molecule
b.Mass f one atom compared with the mass of one atom of hydrogen
c.Mass of one molecule of any substance compared with the mass of one atom of C – 12
d.None of the above

Question 16.
0.001 g of C is required t write a letter with a graphite pencil. The total number of C atoms used in writing the letter is:
a.$5.00 \times 10^{12}$
b.$5 \times 10^{19}$
c.$5.0 \times 10^{24}$
d.$6.023 \times 10^{23}$

Question 17.
One mole of a gas occupies a volume of 22.4 L. This is derived from:
a.Berzelius’s hypothesis
b.Gay- Lussac’s law
d.Dalton’s law

Question 18.
The mass of one C atom is:
a.$6.023 \times 10^{23}$ g
b.$1.99 \times 10^{-23}$g
c.2.00 g
d.12 g

Question 19.
The chemical symbol for barium is:
a.B
b.Ba
c.Be
d.Bi

Question 20.
The chemical symbol P stands for:
a.Phosphorus
b.Potassium
c.Polonium
d.Promethium

Question 21.
A group of atoms chemically bonded together is a (an):
a.Molecule
b.On
c.Salt
d.Element

Question 22.
Adding electrons to an atom will result in a (an):
a.Molecule
b.Anion
c.Cation
d.Salt

Question 23.
When an atom loses electrons, it is called a (an) ______ and has a _____ charge.
a.Anion, positive
b.Cation, positive
c.Anion, negative
d.Cation, negative

Question 24.
The molecule formula $P_{2}O_{5}$ means that:
a.A molecule contains 2 atoms of P and 5 atoms of O
b.The ratio of the mass of P to the mass of O in the molecule is 2:5
c.There are twice as many P atoms in the molecule as there are O atoms
d.The ratio of the mass of P to the ass of O in the molecule is 5:2

Question 25.
The correct symbol for silver is:
a.Ag
b.S
c.Ar
d.AI

Question 26.
A spartame, an artificial sweetener, has the molecular formula $C_{14}H_{18}N_{2}O_{5}$. What is the mass in grams of one molecule? (Atomic weights: C = 12.01, H = 1.008, N = 14.01, O = 16.00)
a.$4.89 \times 10^{-21}$
b.$2.24 \times 10^{-21}$
c.$3.85 \times 10^{-22}$
d.$4.89 \times 10^{-22}$

Question 27.
Morphine, an addictive drug, has the molecular formula $C_{17}H_{19}NO_{3}$. What is the mass in grams of one molecule?(Atomic weights: C = 12.01, H = 1.008, N = 14..1, O = 16.00)
a. $2.24 \times 10^{-22}$
b. $3.85 \times 10^{-22}$
c. $3.85 \times 10^{-21}$
d. $4.74 \times 10^{-22}$

Question 28.
The controversial artificial sweetener saccharin has the molecular formula $C_{3}H_{5}O_{5}NS$. What is the mass in grams of one molecule? Atomic weights: C = 12.01, H = 1.008, O = 16.00, N = 14.01, S = 32.06.
a.$5.55 \times 10^{-21}$
b.$3.85 \times 10^{-22}$
c.$2.24 \times 10^{-22}$
d.$2.24 \times 10^{-21}$

Question 29.
The statue of Liberty is made of 2.0 x 105 Ibs of copper sheets bolted to a framework. (1Ib = 454 g) . How many atoms of copper are on the statue? (Atomic weight: Cu = 63.5.)
a.$2.1 \times 10^{27}$
b.$8.6 \times 10^{29}$
c.$4.3 \times 10^{26}$
d.$8.6 \times 10^{26}$

Question 30.
Selenium ingested in the amount of 90 micrograms per day causes loss of hair. How many selenium atoms are in this size sample? (Atomic weight: Se = 78.96.)
a.$6.9 \times 10^{23}$
b.$8.8 \times 10^{17}$
c.$8.8 \times 10^{22}$
d.$6.9 \times 10^{17}$

Question 31.
Novocain is $C_{13}H_{16}N_{2}O_{2}$ What is the total number of moles of atoms in 0.020 moles of Novocain?
(Atomic weights: C = 12.01, O = 16.00, N = 14.01, H = 1.008.)
a.0.033
b.3.3
c.0.66
d.0.33

Question 32.
Methoxychlor, a garden insecticide, has the molecular formula $C_{16}H_{15}C_{13}O$. What is the total number of moles of atoms in a 3.0 mg sample? (Atomic weights: C = 12.01, H = 1.008, Cl = 35.45, O = 16.00)
a.$8.7 \times 10^{-6}$
b.$3.0 \times 10^{-5}$
c.$3.1 \times 10^{-1}$
d.$3.1 \times 10^{-4}$

Question 33.
What are the total number of moles of atoms in 4.32 g of $Sc(NO_{3})_{3}$?
(Atomic weights: Sc = 45.0, O = 16.00, N = 14.01.)
a.0.0132
b.0.324
c.0.0187
d.0.243

Question 34.
Two samples of lead oxide were separately reduced to metallic lead by heating in a current of hydrogen. The weight of lead from one oxide was half the weight of lead obtained from the other oxide. The data illustrates:
a.Law of reciprocal proportions
b.Law of constant proportions
c.Law of multiple proportions
d.Law of equivalent proportions

Question 35.
The percentage of copper and oxygen in samples of CuO obtained by different methods were found to be the same. The illustrate the law of:
a.Constant proportion
b.Conservation of mass
c.Multiple proportions
d.Reciprocal proportions

Question 36.
The total number of atoms represented by the compound $CuSO_4.5H_2O$ is:
a.27
b.21
c.5
d.8

Question 37.
In compound A, 1.00g of nitrogen unites with 0.57 g of oxygen. In compound B, 2.00g of nitrogen combines with 2.24g of oxygen. In compound C, 3.00g of nitrogen combines with 5.11g of oxygen. These results obey the following law:
a.Law of constant proportion
b.Law of multiple proportion
c.Law of reciprocal proportion
d. Dalton’s law of partial pressure

Question 38.
The weight of a molecule of the compound $C_{60}H_{122}$ is:
a.$1.4 \times 10^{-21}$ g
b.$1.09 \times 10^{-21}$ g
c.$5.025 \times 10^{23}$ g
d.$16.023 \times 10^{23}$ g

Question 39.
The mass of a molecule of water is:
a.$3 \times 10^{-26}$ kg
b.$3 \times 10^{-25 }$kg
c.$1.5 \times 10^{-26}$ kg
d.$2.5 \times 10^{-26}$ kg

Question 40.
The number of atom in 4.25g of $NH_{3}$ is approximately:
a.$1 \times 10^{23}$
b.$2 \times 10^{23}$
c.$4 \times 10^{23}$
d.$6 \times 10^{23}$

Question 41.
Volume of a gas at STP is $1.12 \times 10^{-7}$ cc. Calculate the number of molecules in it:
a.$3.01 \times 10^{20}$
b.$3.01 \times 10^{12}$
c.$3.01 \times 10^{23}$
d.$3.01 \times 10^{24}$

Question 42.
The number of molecules of $CO_{2}$ present in 44g of $CO_{2}$ is:
a.$6.02 \times 10^{23}$
b.$3 \times 10^{23}$
c.$12 \times 10^{23}$
d.$3 \times 10^{10}$

Question 43.
The volume occupied by 4.4g of $CO_2$ at STP is:
a.22.4 L
b.2.24 L
c.0.224 L
d.0.1 L

Question 44.
How many molecules are present in one gram of hydrogen?
a.$6.02 \times 10^{23}$
b.$3.01 \times 10^{23}$
c.$2.5 \times 10^{23}$
d.$1.5 \times 10^{23}$