In sha Allah no mcq will come out of this in the exams...!

1. Chapter 3
Atomic Structure
(Neither take rest nor be the time waste,
Because life is the test and only heaven is
the rest)
Chemistry Def. & MCQs Dr. Sajid Ali Talpur

2.  Definitions
1. Atom: -The building block of the matter that
takes part in the reaction.
OR
The smallest component of an element having
the chemical properties of the element,
consisting of a nucleus and surrounding shells.
2. Nucleus: -the central part of the atom
comprising the mass of the atom conferred by
protons and neutrons, initially discovered by
RUTHERFORD.
3. Shell or energy level: -according to Bohr these
are the circular orbits at certain distance from
the nucleus where electrons exist.
4. Atomic number (Z): -The number of protons in
nucleus is called the atomic number of the
element.
5. Atomic mass: - The total number of protons
and neutrons in nucleus constitute its atomic
mass.
6. Element: -The simplest matter whose all atoms
have same atomic number and can not be further
simplified is called element.
7. Crook’s discharge tube experiment: -
indicates the existence of protons and electrons
in the atom
Chemistry Def. & MCQs Dr. Sajid Ali Talpur

3. 8. Cathode rays: -the rays which consist of
electrons and are produced when the current is
passed through gases at low pressure are called
cathode rays.
9. Properties of cathode rays (electrons):
Discovered by J.J THOSMSON
 Carry a negative charge equal to 1.6*10-
19
C=4.803*10-10
 Their e/m ratio is 1.76*108
C/g
 Their mass is 9.11*10-31
kg = 0.00055a.m.u
 They can be deflected by electromagnetic field.
 These don’t depend upon the material of which
the electrode is made nor of the gas which is
enclosed inside the tube.
10. The properties of canal rays ( protons):
 GOLDSTIEN discovered them.
 These rays carry positive charge
 They travel in straight line
 The value of e/m depends upon the gas enclosed
 The mass is 1.67*10-27
kg=1.0073amu
 They are composed of heavy particles than
electrons.
11. The properties of neutrons:
 Discovered by CHADVICK.
 They are neutral, carrying no charge.
 The mass is same as that of proton but slightly
heavier. i.e. 1.0087 a.m.u.
 It is highly energetic particle.
Chemistry Def. & MCQs Dr. Sajid Ali Talpur

4. 12. Radioactivity: -the spontaneous emission of
radiations by certain elements is called
radioactivit
13. Isotopes: - Atoms of the same elements, having
the same atomic number but the different atomic
masses are called isotopes.
14. Spectrum: -the band of colors formed through
the dispersion of light is called spectrum.
15. Electronic configuration: - the arrangement or
distribution of electrons in the available orbitals
is called electronic distribution.
16. Atomic radius: -the half of the bond length,
taken between two homonuclear diatomic
molecules. OR the distance from nucleus to the
valence electron is called atomic radius.
17. Ionic radius: -the radius of an ion.
18. ion: -the charged atom is called ion
19. Cation: -the positively charged ion is called
cation.
20. Anion: -the negative charged ion is called
anion.
Chemistry Def. & MCQs Dr. Sajid Ali Talpur

5. 21. Ionization potential: -the energy required to
make an atom ion is called ionization potential.
22. Electron affinity: -the amount of energy
released when an electron is added to a neutral
gaseous atom to form a negative ion is called
electron affinity.
23. Electronegativity: - the force with witch an
atom attracts the shared pair towards itself is
called electronegativity.
Chemistry Def. & MCQs Dr. Sajid Ali Talpur

6.  Multiple Choice Questions
1. The first atomic theory was proposed by:
a) Democritus b) Greek Philosophers
c) both a & b d) John Dalton
2. According to modern theory, all elements are
made up of small, indivisible, indestructible
particles called atoms
a) true b) false
3. Protons and neutrons were discovered by
respectively:
a) J.J Thomson, Chadwick
b) Chadwick, J.J Thomson
c) Goldstein, Chadwick
d) Chadwick, Goldstein
4. Electrons are the constituent of all matter.
a) true b) false
5. The incorrect statement regarding the cathode
rays is:
a) material particles
b) e/m ratio is different
c) possess K.E
d) N.O.T
6. Electrons do not depend upon the the nature of
the cathode and the gas inside the tube.
a) true b) false
Chemistry Def. & MCQs Dr. Sajid Ali Talpur

7. 7. e/m ratio of electron is:
a) 1.76*108
C/g b)1.76*1011
C/g
c) 1.602*10-19
C/g d) 1.672*10-27
C/g
8. The Charge on electron is:
a) 1.76*108
C b)1.76*1011
C
c) 1.602*10-19
C d) 1.672*10-27
C
9. The charge on proton is:
a) 1.76*108
b)1.76*1011
C
c) 1.602*10-19
C d) 1.672*10-27
C
10. 1 a.m.u =?
a) 1.76*108
g b)1.76*1011
g
c) 1.602*10-19
g d) 1.672*10-27
g
11. Atom was proved divisible particle by:
a) cathode rays b) radioactivity
c) discharge tube exp. d) A.O.T
12. Electron is 1836 times heavier than proton.
a) true b) false
13. Radioactivity was discovered by:
a) Henry Bequeral b) Rutherford
c) Bohor d) J.J Thomson
14. Rutherford used particles in his experiment.
a) α – particles b) β – particles
c) γ – particles d) A.O.T
Chemistry Def. & MCQs Dr. Sajid Ali Talpur

8. 15. The α-particles deflected back by striking the
atom because of the presence of:
a) shells b) nucleus
c) protons d) electrons
16. Energy is …… when an electron jumps from
higher energy level to lower energy level.
a) absorbed b) released
c) neither absorbed nor released
d) both a & b
17. This of the following particles takes part in the
reaction.
a) electron b) proton
c) neutron d) A.O.T
18. The correct equation is:
a) E2 - E1 = hυ b) E2 + E1 = hυ
c) E2 * E1 = hυ d) E2 / E1 = hυ
19. Na has:
a) 11 electrons b) 11 protons
c) 12 neutrons d) A.O.T
20. Mass number =
a) protons + electrons
b) protons + neutrons
c) electrons + neutrons
d) no. of protons.
Chemistry Def. & MCQs Dr. Sajid Ali Talpur

9. 21. Atomic number =
a) protons + electrons
b) protons + neutrons
c) electrons + neutrons
d) no. of protons.
22. The positively charged particles in radioactivity
are protons.
a) true b) false
23. Isotopes have different number of:
a) electrons b) protons
c) neutrons d) A.O.T
24. Proteum has one proton and no neutron.
a) true b) false
25. Isotopes are used in the treatment of diseases.
a) true b) false
26. The formula to find out max number of
electrons is:
a) n2 b) 2n
c) 2n2 d) N.O.T
27. When n=3 the max electrons in a shell should
be.
a) 3 b) 6
c) 9 d) 18
28. The max. number of electrons in 4th
shell is:
a) 4 b) 8
c) 16 d) 32
Chemistry Def. & MCQs Dr. Sajid Ali Talpur

10. 29. Find the mis match
a) electrons : J.J Thomson
b) protons : nucleus
c) neutrons : atomic mass
d) protons : atomic number
30. The correct statement is:
a) A = Z+A b) A=Z-N
c) A=N-Z d) Z=A-N
31. Which isotope of oxygen forms ozone
a) O16 b) O17
c) O18 d) O19
Answer Key
1 D 2 B 3 C
4 A 5 A 6 B
7 A 8 C 9 C
10 D 11 B 12 B
13 A 14 B 15 A
16 B 17 B 18 A
19 D 20 B 21 D
22 C 23 A 24 A
25 A 26 C 27 D
28 D 29 A 30 D
31 C
Chemistry Def. & MCQs Dr. Sajid Ali Talpur

11. By the same Author:
 How to be successful?
 Definitions of chemistry terms
 Definitions of Physics terms
 Definitions and MCQs on
branches of Biology
 Ninth Class Chemistry MCQs
 Ninth Class Biology MCQs
 Scientific Biological Reasons
Chemistry Def. & MCQs Dr. Sajid Ali Talpur

12.  Definitions, Scientific Reasons
and MCQs on Chemistry
 Skeletal muscles Physiology
BCQs
 How to achieve heaven? The
mechanism of goodness and
badness
 Biology MCQs test for entry
test
 Chemistry MCQs test for entry
test
 Cardiovascular system anatomy
quiz
 Lower limb anatomy quiz
 Lower limb Anatomy MCQs
Chemistry Def. & MCQs Dr. Sajid Ali Talpur

13.  Spiritual successful life
quotations
 Why should one love the Prophet
Muhammad (s.a.w)
 Quotations on the Prophet
Muhammad (s.a.w)
 The origin and future of human
life
 Endocrinology – Hormones MCQs
 Islam, science, success and
wisdom quotes
Chemistry Def. & MCQs Dr. Sajid Ali Talpur