class 9 QUESTION BANK FOR SAII
CHAPTER-3
ATOMS AND MOLECULES
1 Marks Questions :
1. Identify diatomic
Molecules from the following:
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a) HCl
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b) P₄
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c) He
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d) H2S
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e) CO
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2.Name
two polyatomic ions.
3.How many atoms are there
in exactly 12g of carbon element? (C=12)
4.What is Mole?
5.Define the law of
conservation of mass.
6.Give
the name of the elements present in the following compounds :
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a) Quick lime
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b) Baking
power
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c)
Hydrogenbromide
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7. Give two symbols which
have been derived from the ‘Latin Name of the elements.
8.Define
law of constant proportions?
9.How many molecules are
present in 9g of H₂O
11.What is meant by valency
of an element ?
12.What is meant by
Avogadro’s constant ?
13.What is the mass of 1
mol of oxygen atoms ?
14.Name the smallest
particle of an element that can retain all the chemical properties.
15.Write the name of
compound, CaCO₃ ?
16.What is the ratio of
mass of a molecule and its molar mass ?
17.Which number is
represented by 1 mole ?
18.Name the smallest
particle that has all the properties of a compound.
2 Marks Questions :
1.What is meant by the term
atomicity? What is meant by saying that oxygen molecule is diatomic?
2.Write
down the formulae of the following compounds
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a)
BraiumSulphate
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b) Nitric
Acid
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c) Ammonium
nitrate.
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3.Calculate the molar mass
of HNO₃ .
Atomic mass of H = 1u, N = 14u, O = 16u.
4.Calculate the number of
moles in 17g of H2O2.
5.Calculate the molecular
mass of K2CO3 and H2O.
6.Calculate formula unit
mass of Cacl2.
7.What is the difference
between the mass of a molecule and molecular mass?
8.Distinguish between an
atom of an element and a molecule of a compound.
9.Name the Chemical symbols
for the following elements: Iron, Copper, Mercury, Silver and Lead.
10.Write the formula of
aluminium fluoride and aluminium nitride
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12.How many molecules of
carbon dioxide are present in 44 g ?
13.Define
mole. Calculate the number of moles in 22 g of carbon dioxide (Atomic mass of C
= 12u, O = 16u ).
14.What
are polyatomic ions ? Give two examples.
15.What is the utility of
mole concept.
3 Marks Questions :
1.What is an ion? State and
explain the difference between an atom and its ion.
3.(a) Define Avogadro’s
number. Why it is also known as Avagadro constant ?
(b) Calculate the molar
mass of NaO. ( Given, Na = 23u; O = 16 u )
4.Write the chemical
formulae of the following :
(a) Potassium Chloride
(b) Magnesium Hydroxide
(c) Ammonium sulphate
5.What are ionic and
molecular compounds ? Give examples. Why the term molecular mass is not
preferred for use in ionic compounds ?
6.Give an explanation for
the laws of constant proportion on the basis of Dalton’s atomic theory.
7.Which statement of
Dalton’s atomic theory led to the determination of atomic mass of elements ? Explain.
8.Express one atomic mass
unit in grams.
9.Calculate percentage
composition of glucose ( C₆H₁₂O₆ ).
10.In which of the
following cases the number of oxygen atoms is more ?
(a)4.5 g of H₂O
(b)5.05 g CO₂.
5 Marks Questions :
1.Which has more number of
atoms, 100g of sodium or 100 g of iron (given atomic mass of Na =23u, Fe =
56u).
2.Calculate the number of
aluminum ions present in 0.051 gm of aluminum oxide.
3.State
the main points of Dalton’s atomic theory of matter.
4.Calculate
the mass of the following:
(a) 0.5 moles of the N2 gas
(b) 0.5 moles of N atoms
(c) 3.011×1022 number
of N atoms
(d) 6.023×1023 of N2 molecules
5.Calculate
the number of moles for the following:
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(i) 52 g of
He
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(ii)
12.046×1023 number of He atoms.
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CHAPTER -4
STRUCTURE OF ATOM
1 Marks Questions :
1.What is meant by mass
number of an element?
2.What are cathode rays?
3.What thing decides the
chemical properties of an element? Why?
4.Name the radio isotopes
used to :
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a) Detect
Blood clots
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b) Determine
the activity of thyroid gland.
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5.How are the isotopes of
hydrogen represented?
6.The mass number of an
element is 18. It contains 7 electrons what is the number of portions and
neutron in it.
7.State drawback of
Rutherford’s Model of the atom.
8.Write electronic
configuration of sodium.
9.Which particles are
present in the nucleus and what type of charge is there on them?
10.Name a non metal with 6
valence electrons.
11.Why was gold metal foil
selected for alpha-scattering experiment ?
12.How many electrons at
the maximum can be there in the first shell ?
13.Name the isotope of
hydrogen which has the same number of electrons, protons and neutrons.
14.Name
the fundamental particle not present in the nucleus of hydrogen atom.
15.
Define isobars.
2 Marks Questions :
1.What was the main drawbacks
in Rutherford’s model of an atom ?
2.Give brief account of
valency of an atom.
3.Is it possible for the
atom of an atom of an element to have one electron, one proton and no neutron ?
If so, name the element.
4.Gases are bad conductors
of electricity. Then, how do you account for the flow of current in a discharge
tube experiment ?
5.State two main postulates
of Thomson’s model of an atom.
6.Will ³⁵Cl and ³⁷Cl have different
valencies. Justify your answer.
7.Write any two
observations which support the fact that atoms are divisible.
8.Describe the magnitude of
the size of an atom in comparison to its nulear size.
9.Comment on the statement
that “ electrons are common constituents of all matter “.
10.Which of the following
two particles have identical values of charge/mass ? Explain. Proton,
deuterium, neutron and tritium.
11.Give the essential
features of the experiment that led to the discovery of isotopes.
12.If the symbolic
representation of an atom is ⁶ X₃, What is its valency, name and also give the
reason for the valency ?
13.What are the differences
in the discharge tubes used to study cathode rays and the positive rays ?
14.Radioisotope dating is a
technique used to determine the age of old wooden objects of archaeological
importance. Explain.
15.‘A’ has 9 protons, 9
electrons and 10 neutrons. ‘B’ has 12 protons, 12 electrons and 12 neutrons.
Write the formula of the compound formed between A and B.
3 Marks Questions :
1.State three ways by which
a proton differs from an electrons.
2.What are isotopes? Give
two examples?
3.The mass number of an
element is 197 amu and its atomic number is 79. Find the number of electrons,
protons and neutrons.
4.What
are the limitations of Rutherford model of the atom?
5.Define valency by taking
examples of silicon and oxygen.
6.Expalin the arrangement
of electrons outside the nucleus.
8.In what way is the
Rutherford’s atomic model different from that of Thomson’s atomic model ?
9.How were canal rays were
discovered ?
10.Compare an electron, a
proton and a neutron in respect of their symbols, mass and charge.
5 Marks Questions :
1.Explain Thomson’s model
of an atom and write the limitations of J.J. Thomson’s what are isotopes? Give
two examples? Make model of the atom.
2.Compare the proportion of
electrons, protons and neutrons.
3.Describe the Rutherford’s
experiment that led the discovery of nucleus?
4.Give the main postulates
of Bohr’s model of atom.
5.Distinguish between
isotopes and Isobars .Write the application of Isotopes.
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