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Chemistry
Structure of the Atom
NCERT Solutions
NCERT Solutions
Structure of the Atom
34 Solutions
Exercise:
All Exercises
Exercises
In-text Questions (Section 4.1)
In-text Questions (Section 4.2.3)
In-text Questions (Section 4.2.4)
In-text Questions (Section 4.3)
In-text Questions (Section 4.4)
In-text Questions (Section 4.5.2)
In-text Questions (Section 4.6.1)
Q1
Exercises
Compare the properties of electrons, protons and neutrons.
Q2
Exercises
What are the limitations of J.J. Thomson's model of the atom?
Q3
Exercises
What are the limitations of Rutherford's model of the atom?
Q4
Exercises
Describe Bohr's model of the atom.
Q5
Exercises
Compare all the proposed models of an atom given in this chapter.
Q6
Exercises
Summarise the rules for writing of distribution of electrons in various shells for the first eighteen elements.
Q7
Exercises
Define valency by taking examples of silicon and oxygen.
Q8
Exercises
Explain with examples (i) Atomic number, (ii) Mass number, (iii) Isotopes and iv) Isobars. Give any two uses of isotopes.
Q9
Exercises
N
a
+
\mathrm{Na}^{+}
Na
+
has completely filled K and L shells. Explain.
Q10
Exercises
If bromine atom is available in the form of, say, two isotopes
35
79
B
r
(
49.7
%
)
{}_{35}^{79} \mathrm{Br}(49.7 \%)
35
79
Br
(
49.7%
)
and
35
81
B
r
(
50.3
%
)
{}_{35}^{81} \mathrm{Br}(50.3 \%)
35
81
Br
(
50.3%
)
, calculate the average atomic mass of bromine atom.
Q11
Exercises
The average atomic mass of a sample of an element X is 16.2 u . What are the percentages of isotopes
8
16
X
\quad {}_{8}^{16} \mathrm{X}
8
16
X
and
8
18
X
{}_{8}^{18} \mathrm{X}
8
18
X
in the sample?
Q12
Exercises
If
Z
=
3
Z=3
Z
=
3
, what would be the valency of the element? Also, name the element.
Q13
Exercises
Composition of the nuclei of two atomic species X and Y are given as under
X
Y
Protons
= 6
6
Neutrons
= 6
8
Give the mass numbers of X and Y . What is the relation between the two species?
Q14
Exercises
For the following statements, write T for True and F for False.
(a)
J.J. Thomson proposed that the nucleus of an atom contains only nucleons.
(b)
A neutron is formed by an electron and a proton combining together. Therefore, it is neutral.
(c)
The mass of an electron is about
1
2000
\frac{1}{2000}
2000
1
times that of proton.
(d)
An isotope of iodine is used for making tincture iodine, which is used as a medicine.
Q15
Exercises
Rutherford's alpha-particle scattering experiment was responsible for the discovery of
(a)
Atomic Nucleus
(b)
Electron
(c)
Proton
(d)
Neutron
Q16
Exercises
Isotopes of an element have
(a)
the same physical properties
(b)
different chemical properties
(c)
different number of neutrons
(d)
different atomic numbers.
Q17
Exercises
Number of valence electrons in
C
l
−
\mathrm{Cl}^{-}
Cl
−
ion are:
(a)
16
(b)
8
(c)
17
(d)
18
Q18
Exercises
Which one of the following is a correct electronic configuration of sodium?
(a)
2,8
(b)
8,2,1
(c)
2,1,8
(d)
2,8,1.
Q19
Exercises
Complete the following table.
Atomic Number
Mass Number
Number of Neutrons
Number of Protons
Number of Electrons
Name of the Atomic Species
9
-
10
-
-
-
16
32
-
-
-
Sulphur
-
24
-
12
-
-
-
2
-
1
-
-
-
1
0
1
0
-
Q1
In-text Questions (Section 4.1)
What are canal rays?
Q2
In-text Questions (Section 4.1)
If an atom contains one electron and one proton, will it carry any charge or not?
Q1
In-text Questions (Section 4.2.3)
On the basis of Thomson's model of an atom, explain how the atom is neutral as a whole.
Q2
In-text Questions (Section 4.2.3)
On the basis of Rutherford's model of an atom, which subatomic particle is present in the nucleus of an atom?
Q3
In-text Questions (Section 4.2.3)
Draw a sketch of Bohr's model of an atom with three shells.
Q4
In-text Questions (Section 4.2.3)
What do you think would be the observation if the
α
\alpha
α
-particle scattering experiment is carried out using a foil of a metal other than gold?
Q1
In-text Questions (Section 4.2.4)
Name the three sub-atomic particles of an atom.
Q2
In-text Questions (Section 4.2.4)
Helium atom has an atomic mass of 4 u and two protons in its nucleus. How many neutrons does it have?
Q1
In-text Questions (Section 4.3)
Write the distribution of electrons in carbon and sodium atoms.
Q2
In-text Questions (Section 4.3)
If K and L shells of an atom are full, then what would be the total number of electrons in the atom?
Q1
In-text Questions (Section 4.4)
How will you find the valency of chlorine, sulphur and magnesium?
Q1
In-text Questions (Section 4.5.2)
If number of electrons in an atom is 8 and number of protons is also 8, then (i) what is the atomic number of the atom? and (ii) what is the charge on the atom?
Q2
In-text Questions (Section 4.5.2)
With the help of Table 4.1, find out the mass number of oxygen and sulphur atom.
Q1
In-text Questions (Section 4.6.1)
For the symbol H, D and T tabulate three sub-atomic particles found in each of them.
Q2
In-text Questions (Section 4.6.1)
Write the electronic configuration of any one pair of isotopes and isobars.
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