WorksheetsClass 9 Structure of Atom
Total questions: 45
Worksheet time: 45mins
Rutherford’s alpha particle scattering experiment led to the discovery of :
(a) Nucleus
(b) Electrons
(c) Protons
(d) Neutrons
Which of the following is the correct electronic configuration of sodium ?
2,8,1
8,2,1
2,1,8
2,8,2
The particle not present in an ordinary hydrogen atom is :
proton
neutron
nucleus
electron
The subatomic particle called electron was discovered by:
J. J. Thompson
Neils Bohr
James Chadwick
E. Goldstein
Which of the following represents the correct electron distribution in magnesium ion ?
2,8
2,8,1
2,8,2
2,8,3
The correct electronic configuration of a chloride ion is :
2,8
2,8,4
2,8,8
2,8,7
Goldstein’s experiments which involved passing high voltage electricity through gases at very low pressure
resulted in the discovery of
Electron
Proton
Nucleus
Neutron
The number of electrons in the atom of an element X is 15 and the number of neutrons is 16. Which of the following is the correct representation of an atom of this element ?
The ion of an element has 3 positive charges. The mass number of atom of this element is 27 and the
number of neutrons is 14. What is the number of electrons in the ion ?
13
10
14
16
The first model of an atom was given by :
Neils Bohr
Ernest Rutherford
J.J. Thomson
Eugen Goldstein
Which of the following statement is always correct ?
an atom has equal number of electrons and protons
an atom has equal number of electrons and neutrons
an atom has equal number of protons and neutrons
an atom has equal number of electrons, protons and neutrons
The mass number of two atoms X and Y is the same (40 each) but their atomic numbers are different (being
20 and 18 respectively). X and Y are examples of :
Chemically similar atoms
isotopes
solid and liquid metals
isobars
Which of the following statement is correct about the atom of an element ?
an atom can have only protons and neutrons but no electrons.
an atom can have only electrons and neutrons but no protons
an atom can have only electron and proton but no neutron
an atom must always have a proton, neutron and electron
There are two species represented as 35Cl and 37Cl. Which of the following statement is correct regarding
these species ?
they have different chemical properties
their physical properties are the same
they have the same number of protons
they are isobars of the same element
The radioactive isotope used in the treatment of cancer is :
plutonium-239
arsenic-74
cobalt-60
iodine-131
Elements having valency ‘one’ are :
always metals
always non-metals
always metalloids
either metals or non-metal
In a sample of ethyl ethanoate (CH3COOC2H5), the two oxygen atoms have the same number of electrons
but different number of neutrons. Which of the following is the correct reason for it ?
one of the oxygen atoms has gained electrons
one of the oxygen atoms has gained protons
the two oxygen atoms are isotopes
the two oxygen atoms are isobars
Which of the following elements does not exhibit electrovalency ?
Calcium
Chromium
Carbon
Cadmium
The number of valence electrons in a graphite atom is :
2
4
3
5
The atomic numbers of four elements A, B, C and D are 12, 13, 15 and 3 respectively. The element whichcannot form a cation is :
A
B
C
D
The number of valence electrons in a sulphide ion, S2–, is :
16
10
9
8
For an element, Z = 9. The valency of this element will be :
4
2
1
3
Four elements W, X, Y and Z contain 8, 11, 9 and 17 protons per atom respectively. The element which
cannot form an anion is most likely to be :
W
X
Y
Z
The four atomic species can be represented as follows. Out of these, the two species which can be termedisobars are :
(i) and (ii)
(ii) and (iii)
(i) and (iii)
(i) and (iv)
There are four elements P, Q, R and S having atomic numbers of 4, 18, 10 and 16 respectively. The element
which can exhibit covalency as well as electrovalency will be :
P
Q
R
S
The atomic number of an element X is 8 and that of element Y is 4. Both these elements can exhibit a valency of :
1
2
3
4
The isotopes of an element contain :
same number of neutrons but different number of protons
same number of neutrons but different number of electrons
different number of protons as well as different number of neutrons
different number of neutrons but same number of protons
Which of the following correctly represent the electronic distribution in the
Mg atom?
3, 8, 1
2, 8, 2
1, 8, 3
8, 2, 2
Rutherford’s ‘alpha (α) particles scattering experiment’ resulted in to
discovery of
Electron
Proton
Nucleus in the atom
Atomic Mass
The number of electrons in an element X is 15 and the number of neutrons
is 16. Which of the following is the correct representation of the element?
Dalton’s atomic theory successfully explained (i) Law of conservation of mass
(ii) Law of constant composition (iii) Law of radioactivity (iv) Law of multiple proportion
(i), (ii) and (iii)
(i), (iii) and (iv)
(ii), (iii) and (iv)
(i), (ii) and (iv)
Which of the following statements about Rutherford’s model of atom are correct? (i) considered the nucleus as positively charged (ii) established that the α–particles are four times as heavy as a hydrogen atom
(iii) can be compared to solar system (iv) was in agreement with Thomson’s model
(i) and (iii)
(ii) and (iii)
(i) and (iv)
only (i)
Which of the following are true for an element? (i) Atomic number = number of protons + number of electrons
(ii) Mass number = number of protons + number of neutrons (iii) Atomic mass = number of protons = number of neutrons (iv) Atomic number = number of protons = number of electrons
(i) and (ii)
(i) and (iii)
(ii) and (iii)
(ii) and (iv)
In the Thomson’s model of atom, which of the following statments are correct? (i) the mass of the atom is assumed to be uniformaly distributed over the atom (ii) the positive charge is assumed to be uniformaly distributed over the atom (iii) the electrons are uniformaly distributed in the positively charged sphere (iv) the electrons attract each other to stabilise the atom
(i), (ii) and (iii)
(i) and (iii)
(i) and (iv)
(i), (iii) and (iv)
Rutherford’s α–particle scattering experiment showed that (i) electrons have negative charge (ii) the mass and positive charge of the atom is concentrated in the nucleus (iii) neutron exists in the nucleus (iv) most of the space in atom is empty Which of the above statements are correct?
(i) and (iii)
(ii) and (iv)
(i) and (iv)
(iii) and (iv)
The ion of an element has 3 positive charges. Mass number of the atom is 27 and the number of neutrons is 14. What is the number of electrons in the ion?
13
10
14
16
Identify the Mg2+ ion from the Fig.4.1 where, n and p represent the number
of neutrons and protons respectively
In a sample of ethyl ethanoate (CH3COOC2H5) the two oxygen atoms have the same number of electrons but different number of neutrons. Which of the following is the correct reason for it?
One of the oxygen atoms has gained electrons
One of the oxygen atoms has gained two neutrons
The two oxygen atoms are isotopes
The two oxygen atoms are isobars
Elements with valency 1 are
always metals
always metalloids
either metals or non-metals
always non-metals
The first model of an atom was given by
N. Bohr
E. Goldstein
Rutherford
J.J. Thomson
An atom with 3 protons and 4 neutrons will have a valency of
3
7
1
4
The electron distribution in an aluminium atom is
2, 8, 3
2, 8, 2
8, 2, 3
2, 3, 8
Which of the following in Fig. 4.2 do not represent Bohr’s model of an atom correctly?
(i) and (ii)
(ii) and (iii)
(ii) and (iv)
(i) and (iv)
Which of the following statement is always correct?
An atom has equal number of electrons and protons.
An atom has equal number of electrons and neutrons
An atom has equal number of protons and neutrons.
An atom has equal number of electrons, protons and neutrons.
Atomic models have been improved over the years. Arrange the following atomic models in the order of their chronological order (i) Rutherford’s atomic model (ii) Thomson’s atomic model (iii) Bohr’s atomic model
(i), (ii) and (iii)
(ii), (iii) and (i)
(ii), (i) and (iii)
(iii), (ii) and (i)
