CBSE Questions for Class 9 Chemistry Atoms And Molecules Quiz 9 - MCQExams.com

Which of the following term is denoted as Formula Mass Unit?
  • Compounds
  • Molecules
  • Molecules contains ions as constituents
  • None
Which of the following statements are not summarized within Dalton's Atomic Theory?
  • Atoms cannot be created or destroyed.
  • Atoms are made of protons, neutrons and electrons.
  • Atoms rearrange in chemical reactions.
  • When atoms combine to form compounds, they combine in whole number ratios.
What is the molar mass of ammonium carbonate $${({NH}_{4})}_{2}{CO}_{3}$$?
  • $$48\ g/mol$$
  • $$96\ g/mol$$
  • $$82\ g/mol$$
  • $$78\ g/mol$$
  • $$192\ g/mol$$
Zinc sulphate contains 22.65% Zn and 43.9% $$H_2O$$. If the law of constant proportions is true, then the mass of zinc required to give 40 g crystals will be:
  • 90.6 g
  • 9.06 g
  • 0.906 g
  • 906 g
Select the smallest atom.
  • $$F$$
  • $$Cl$$
  • $$Br$$
  • $$I$$
How many grams are there in a $$7.0$$ mole sample of sodium hydroxide?
  • $$40.0g$$
  • $$140.0\ g$$
  • $$280.0\ g$$
  • $$340.0\ g$$
  • $$420.0\ g$$
The image below represents the formation of potassium bromide, $$KBr$$. Which law is represented by this reaction?
528586.jpg
  • Law of Conservation of Mass
  • Law of Multiple Proportions
  • Law of Definite Proportions
  • Law of Stoichiometry
The reaction between dinitrogen monoxide, $$N_{2}O$$ and oxygen gas, $$O_{2}$$, carried out at high pressures, results in the formation of dinitrogen tetroxide, $$N_{2}O_{4}$$, as the only product. The unbalanced equation for the reaction is:

$$N_{2}O(g) +O_{2}(g)\rightarrow N_{2}O_{4}(g)$$

Given the legend and the $$N_{2}O/O_{2}$$ mixture shown below.
Which of the following represents the composition of the system after the reaction has gone to completion?

532975.jpg
A student carries out the following reaction in the laboratory:

Sodium carbonate + Copper sulphate $$\rightarrow $$ Copper carbonate + Sodium sulphate

How could you determine the reaction obeyed the law of conservation of mass?
  • Mass of the sample after the reaction is compared to the mass before the reaction begins
  • Mass of the sample as the reaction is run is measured
  • Filtering the reactants
  • Running the reaction in an open system
What is the formula unit mass of sodium chloride?
  • 58.5
  • 35.5
  • 23
  • 40
Identify the anion from $$KClO_3$$.
  • $$Cl^-$$
  • $$O^{2-}$$
  • $$ClO_3{^-}$$
  • None of the above
What is the formula mass unit of $$HCl$$ ?
  • $$36.5$$
  • $$35.5$$
  • $$32.5$$
  • $$34.5$$
Which of the following correctly represents Dalton's symbols?

618644_5f609c409bb3482ca168317973bc3988.png
  • 1 : Oxygen, 2 : Hydrogen, 3: Nitrogen, 4: Carbon and 5: Sulphur
  • 1 : Hydrogen, 2 : Nitrogen, 3: Oxygen, 4: Carbon and 5: Sulphur
  • 1 : Hydrogen, 2 : Nitrogen, 3: Oxygen, 4: Sulphur and 5: Carbon
  • 1 : Hydrogen, 2 : Carbon, 3: Oxygen, 4: Sulphur and 5: Nitrogen
Which of the following would weight the least?
  • $$2$$ gram atoms of nitrogen
  • $$1$$ mole of silver
  • $$22.4$$ liters of oxygen gas at $$1$$ atmospheric pressure and $$273$$ K.
  • $$6.02 \times 10^{23}$$ atoms of carbon.
State whether the given statement is true or false:

An atom is electrically neutral.
  • True
  • False
An ion is produced as a result of gain or loss of electrons by an atom.  In $$Au^{3+}$$ ion, 3 electrons are ___________by $$Au$$ atom.
  • gained
  • lost
  • shared
  • None of the above
When the size of a spherical nanoparticle decreases from $$\text {30 nm}$$ to $$\text {10 nm}$$. The ratio surface area/volume becomes:
  • $$1/3$$ of the original
  • $$3$$ times the original
  • $$1/9$$ of the original
  • $$9$$ times the original
The law of constant proportions was enunciated by: 
  • Dalton
  • Berthelot
  • Avogadro
  • Proust
How many moles of bromine water will be required to complete bromination of 6 moles of phenol?
  • $$6$$
  • $$18$$
  • $$12$$
  • $$3$$
Which one of the following atoms will have largest size?
  • Ca
  • Na
  • Mg
  • Be
Hydrogen combines with chlorine to form HCI. It also combines with sodium to form NaH. If sodium and chlorine also combine with each other, they will do so in the ratio of their masses as:
  • 23 : 35.5
  • 35.5 :23
  • 1 : 1
  • 23 : 1
Atomic size is of the order of____________.
  • $${10}^{-7} cm$$
  • $${10}^{-10} cm$$
  • $${10}^{-13} cm$$
  • $${10}^{-6} cm$$
$$SO_2$$ gas was prepared by
(i) burning sulphur in oxygen,
(ii) reacting sodium sulphite with dilute $$H_2SO_4$$ and
(iii) heating copper with $$conc. H_2SO_4$$. It was found that in each case sulphur and oxygen combined in the ratio of 1 :The data illustrates the law of :
  • conservation of mass
  • multiple proportions
  • constant proportions
  • reciprocal proportions
$$1$$ mole of a compound contains $$1$$ mole of $$C$$ and $$2$$ moles of $$O$$. The molecular weight of the compound is :
  • 3
  • 12
  • 32
  • 44
A sample of $$CaCO_3$$ has Ca - 40%, C = 12% and O = 48%. If the law of constant proportions is true, then the mass of Ca in 5 g of $$CaCO_3$$ from another source will be:
  • 2.0 g
  • 0.2 g
  • 0.02 g
  • 20.0 g
The number of electrons in one molecule of $$CO_{2}$$ are:
  • $$22$$
  • $$44$$
  • $$66$$
  • $$88$$
If one mole contains $$1.0 \times 10^{24}$$ particles, the mass of one mole of oxygen is:
  • 53.2 g
  • 5.32 g
  • 32.0 g
  • 16.0 g
The charge on 1 gram of $$Al^{3+}$$ ions is (e=electronic charge):
  • $$\dfrac{1}{27}N_Ae\, coulomb$$
  • $$\dfrac{1}{3}N_Ae\, coulomb$$
  • $$\dfrac{1}{9}N_Ae\, coulomb$$
  • $$ 3\, N_Ae\, coulomb$$
Law of constant composition is same as the law of:
  • conservation of mass
  • conversation of energy
  • multiple proportion
  • definite proportion
The haemoglobin from red corpuscles of most mammals contains approximately 0.33% of iron by weight. The molecular weight of haemoglobin is 67,The number of iron atoms in each molecule of haemoglobin is:
  • 1
  • 2
  • 3
  • 4
The number of electrons which will together weight one gram is :
  • $$1.098 \times 10^{27}$$electrons
  • $$9.1096\times 10^{31} $$ electrons
  • $$1$$ electron
  • $$1\times 10^4 $$ electrons
The ratio of radius of the nucleus to the radius of the atom is of the order:
  • $$10^5$$
  • $$10^6$$
  • $$10^{-5}$$
  • $$10^{-8}$$
How many moles of oxygen gas can be produced during electrolytic decomposition of $$180 \ g$$ of water?
  • 2.5 moles
  • 5 moles
  • 10 moles
  • 7 moles
$$X\ gm$$ $$A$$ atoms on combining with $$Y$$ atoms of $$B$$ form 5 molecules of a compound containing $$A$$ & $$B$$. Find the molecular weight of compound formed. (Atomic weight of $$B = M$$)
  • $$\dfrac { \left( X{ N }_{ A }+MY \right) }{ 5 } $$
  • $$\dfrac { X+M }{ 5 } \\ $$
  • $$\dfrac { X+MY }{ 5 } $$
  • $$\left( \dfrac { X+MY{ N }_{ A } }{ 5 } \right) $$
Which symbol is used to represent the unit of atomic mass, amu?
  • u
  • A
  • M
  • n
4.88 g of $$KClO_3$$ when heated produced 1.92 g of $$O_2$$ and 2.96 g of KCl. Which of the following statements regarding the experiment is correct?
  • The result illustrates the law of conservation of mass.
  • The result illustrates the law of multiple proportions.
  • The result illustrates the law of constant proportion.
  • None of the above laws is being illustrated here.
Which of the following statements best explains the law of conservation of mass, concerning a chemical change?
  • 100 g of water is heated to give steam.
  • A sample of $$N_2$$ gas is heated at constant pressure without any change in mass.
  • 36 g of carbon combines with 32 g of oxygen to form 68 g of $$CO_2$$.
  • 10 g of carbon is heated in vacuum without any change in mass.
In an experiment, $$2.4\  g$$ of iron oxide on reduction with hydrogen gave $$1.68\  g$$ of iron. In another experiment, $$2.69\  g$$ of iron oxide gave $$1.88 \ g$$ of iron on reduction. Which law is illustrated from the above data?
  • Law of constant proportions
  • Law of multiple proportions
  • Law of reciprocal proportions
  • Law of conservation of mass
Decreasing order of atomic weight is correct of the elements given below?
  • $$Fe > Co > Ni$$
  • $$Ni > Co > Fe$$
  • $$Co > Ni > Fe$$
  • $$Co > Fe > Ni$$
Choose the correct answers from the alternative given.
Who among the following proposed that atom is indivisible?
  • Dalton
  • Berzelius
  • Rutherford
  • Avogadro
If water samples taken from the sea, rivers, lakes or snow-capped mountains, are found to contain hydrogen and oxygen in the ratio of $$1: 8$$. This demonstrates:
  • The law of chemical equilibrium
  • The law of definite proportions
  • Avogadro's law
  • The modern periodic law
How much copper is present in $$50\ g$$ of $$CuSO_4$$?
  • $$19.90\ g$$
  • $$39.81\ g$$
  • $$63.5\ g$$
  • $$31.71\ g$$
Fill in the blanks by choosing the correct options.
924873_57bcc30fc4c846a1805770fc82628fa8.png
  • $$X= 6.023\times 10^{23}$$ moleccules
    $$Y= 22.4L$$ at any pressure
    $$Z=$$ Gram molecular mass
  • $$X= 6.023\times 10^{23}$$ atoms/moleccules
    $$Y= 22.4L$$ at NTP
    $$Z=$$ Gram atomic mass
  • $$X=6.023\times 10^{23}$$ atoms
    $$Y= 22.4L$$ at any temperature
    $$Z=1 $$ gram mole 
  • $$X=6.023\times 10^{23}$$ particles
    $$Y= 11.2L$$ at NTP
    $$Z=$$ Molar volume 
The mass of one mole of  a substance in gram is called its:
  • molecular mass
  • molar mass
  • Avogadro's mass
  • formula mass
Which of the following correctly represents 180 g of water?
(i) 5 moles of water
(ii) 10 moles of water
(iii) $$6.023 \times 10^{23}$$ molecules of water
(iv) $$6.023 \times 10^{24}$$ molecules of water
  • (i)
  • (ii)
  • (iii)
  • (iv)
The density of a gaseous substance at 1 atm pressure and 773 K is 0.4g/lit. If the molecular weight of the substance is 30 the forces existing among gas molecules are?
  • repulsive
  • attractive
  • both
  • none
The number of atoms present in $$16g$$ of oxygen is:
  • $$6.02\times { 10 }^{ 15 }$$
  • $$3.01\times { 10 }^{ 23 }$$
  • $$3.01\times { 10 }^{ 15 }$$
  • $$6.02\times { 10 }^{ 23 }$$
What is the proportion of hydrogen and oxygen by weight in water?
  • $$1:16$$
  • $$1:8$$
  • $$16:1$$
  • $$18:1$$
Insulin contains 3.4% sulphur by mass. What will be minimum molecular weight of insulin?
  • $$94.117$$
  • $$1884$$
  • $$941.7$$
  • $$976$$
$$0.1g \ CaCO_3$$ will contain:
  • $$0.1 N_A \ Ca^{2-}\ ion$$
  • $$0.01N_A \ Ca^{2+} \ ion$$
  • $$0.001 N_A \ Ca^{2+}\ ion$$
  • $$N_A\ Ca^{2+}\ ion$$
0:0:1


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