Atomic Structure | Chemistry | Science - One Mark Questions Answers | 9th Science : Chemistry : Atomic Structure
Chapter: 9th Science : Chemistry : Atomic Structure
One Mark Questions Answers
CHEMISTRY
ATOMIC
STRUCTURE
TEXT BOOK EXERCISES
I. Choose the correct answer :
1.
Among the following the odd pair is
(a)
188O, 199F
(b)
4018Ar, 147N
(c)
3014Si, 3115P
(d)
4020Cr, 3919K
[Answer: (b) 4018Ar, 147N]
2.
Change in the number of neutrons in an atom changes it to
(a)
an ion.
(b)
an isotope.
(c)
an isobar.
(d)
another element.
[Answer: (b) an isotope]
3.
The term nucleons refer to
(a)
protons and electrons
(b)
only neutrons
(c)
electrons and neutrons
(d)
protons and neutrons
[Answer: (d) protons and neutrons]
4.
The number of protons, neutrons and electrons present respectively in 8035Br
are
(a)
80, 80, 35
(b)
35, 55, 80
(c).
35, 35, 80
(d)
35, 45, 35
[Answer: (d) 35, 45, 35]
5.
The correct electronic configuration of potassium is
(a)
2,8,9
(b)
2,8,1
(c)
2, 8, 8, 1
(d)
2, 8, 8, 3
[ Answer: (c) 2, 8, 8, 1]
II. State true or false. If false, correct the statement:
1. In an
atom, electrons revolve around the nucleus in fixed orbits.
Answer: True.
2. Isotopes
of an element have different atomic numbers.
Answer: False.
Correct statement: Same
atomic numbers but different mass numbers.
3. Electrons
have negligible mass and charge.
Answer: True.
4.
Smaller
the size of the orbit, lower is the energy of the orbit.
Answer: True.
5. The
maximum number of electron in L Shell is 10.
Answer: False.
Correct statement : The maximum number of electrons
in L Shell is 8.
III. Fill in the blanks :
1. Calcium
and Argon are examples of a pair of isobars.
2.
Total
number of electrons that can be accommodated in an orbit is given by the formula 2n2.
3. Uranium-235 isotope is used in the nuclear
reactors.
4. The
number of neutrons present in 37Li is 4 .
5.
The
valency of Argon is Zero.
IV. Match the following :
a)
Dalton - 1. Hydrogen atom model
b)
Chadwick - 2. Discovery of nucleus
c)
Rutherford - 3. First atomic theory
d)
Neils Bohr - 4. Plum pudding model
5. Discovery of neutrons
Answer: a - 3, b - 5, c - 2, d - 1.
a) Dalton - First atomic theory
b) Chadwick - Discovery of neutrons
c) Rutherford - Discovery of nucleus
d) Neils Bohr - Hydrogen atom model
V. Complete the following table :
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