ST

NEGELE IFA BORU SPECIAL BOARDING SHOOL 1 SEMESTER CHEMISTRY PRE-

EXAM FOR GRADE 9 STUDENTS IN 2016
226
1. The number of neutrons in an atom of 88Ra is:
a. 88 b 138 c. 82 d 314
2. Which of the following are usually found in the nucleus of an atom?
a. Protons and neutrons only
b. Protons, neutrons and electrons
c. Neutrons only
d. Electrons and neutrons only
3. An atom has an atomic number of 31 and a mass numbers of 70. How many
electrons will it have in its valence shell? a .5 b. 3 c. 4 d. 2
4. Which of the following has a positive charge?
(a) Electrons
(b) Protons
(c ) Neutrons
(d) None of the above
5. Neutrons and protons are collectively known as
(a) Nucleons
(b) Mass number
(c ) Atomic number
(d) None of the above
6. The number of protons in an atom is equivalent to the number of
(a) Neutrons
(b) Protons
(c ) Electrons
(d) None of the above
7. Name the scientist who was first to propose the atomic theory of an atom?
(a) J. J. Thomson
(b) John Dalton
(c ) Neils Bohr
(d) None of the above
8. Which was identical to alpha particles in the Rutherford scattering experiment?
(a) Hydrogen nucleus
(b) Helium nucleus
(c ) Lithium nucleus
(d) None of the above
9. Rutherford’s alpha particle scattering experiment led to the discovery of;
(a) Nucleus
(b) Electrons
(c) Protons
(d) Neutrons
10. Which of the following is the correct electronic configuration of sodium?
(a) 2, 8, 1
(b) 8, 2, 1
(c) 2, 1, 8
(d) 2, 8, 2
11. The particle not present in an ordinary hydrogen atom is:
(a) Proton
(b) Neutron
(c) Nucleus
(d) Electron
12. The subatomic particle called electron was discovered by:
(a) J.J. Thomson
(b) Neils Bohr
(c) James Chadwick
(d) E. Goldstein
13. Which of the following represents the correct electron distribution in magnesium ion?
(a) 2, 8
(b) 2, 8, 1
(c) 2, 8, 2
(d) 2, 8, 3
14. The correct electronic configuration of a chloride ion is:
(a) 2, 8
(b) 2, 8, 4
(c) 2, 8, 8
(d) 2, 8, 7
15. Goldstein’s experiments which involved passing high voltage electricity through
gases at very low pressure, resulted in the discovery of:
(a) Electron
(b) Proton
(c) Nucleus
(d) Neutron.
16. 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?
(a) 15X31
(b) 16X31
(c) 15X16
(d) 16X15
17. The ion of an element has 3 positive charges. The mass number of this element is
27, and the number of neutrons is 14. What is the number of electrons in the ion?
(a) 13
(b) 10
(c) 14
(d) 16.
18. The first model of an atom is given by:
(a) Neils Bohr
(b) Ernest Rutherford
(c) J.J. Thomson
(d) Eugen Goldstein.
19. Which of the following statement is always correct?
(a) An atom has an equal number of electrons and protons
(b) An atom has an equal number of electrons and neutrons
(c) An atom has an equal number of protons and neutrons
(d) An atom has an equal number of electrons, protons and neutrons.
20. Which of the nuclear particles is present in the same fixed number in the atoms of
any particular element?
a. electron b. proton c. neutron
21. Which of the following statements is true?
(a) Thomson proposed that the nucleus of an atom contains protons and neutrons.
(b) The cathode rays obtained from all the gases consist of negatively charged particles
called electrons.
(c) The anode rays obtained from all the gases consist of positively charged particles
called protons.
22. Which of the following concepts was not considered in Rutherford’s atomic model?

A) The electrical neutrality of atom

B) The quantization of energy

C) Electrons revolve around the nucleus at very high speed

D) Existence of nuclear forces of attraction on the electrons

23. 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 ii. Bohr’s atomic model

A) (i), (ii) and (iii) C) (ii), (i) and (iii)

B) (ii), (iii) and (i) D) (iii), (ii) and (i)
24. Which of the following atomic model is also known as Plum-pudding model?

A) Thomson’s atomic model C) Dalton’s atomic model

B) Bohr’s atomic model D) Rutherford’s atomic model

25. In the atomic model nicknamed the “plum pudding” model, what do the plums
represent?

A) The nucleus C) the electrons

B) The atom D) the positive material
26. Rutherford carried out experiments in which a beam of alpha particles was directed
at a thin piece of metal foil. From these experiments he concluded that:

(a) electrons are massive particles.

(b) the positively charged parts of atoms are moving about with a velocity approaching
the speed of light.

(c) the positively charged parts of atoms are extremely small and extremely heavy
particles.

(d) the diameter of an electron is approximately equal to that of the nucleus.

(e) electrons travel in circular orbits around the nucleus.

27.Consider the species 7230Zn, 75As and 74Ge. These species have:

(a) the same number of electrons.

(b) the same number of protons.

(c) the same number of neutrons.

(d) the same number of protons and neutrons.

(e) the same mass number.

28.The neutral atoms of all of the isotopes of the same element have

(a) different numbers of protons.

(b) equal numbers of neutrons.

(c) the same number of electrons.

(d) the same mass numbers.

(e) the same masses.

29. What is the atomic weight of a hypothetical element consisting of two isotopes, one
with mass = 64.23 amu (26.0%), and one with mass = 65.32 amu?

(a) 65.3 amu

(b) 64.4 amu

(c) 64.9 amu

(d) 65.0 amu

(e) 64.8 amu

30. Naturally occurring rubidium consists of just two isotopes. One of the isotopes
consists of atoms having a mass of 84.912 amu; the other of 86.901 amu. What is the
percent natural abundance of the heavier isotope? The Periodic Table confirms an
average atomic mass for Rb = 85.47 amu

(a) 15%

(b) 28%

(c) 37%

(d) 72%
(e) 85%
31. Who proposed the first atomic theory based on philosophical reasoning?

(a) Albert Einstein

(b) John Dalton

(c) Ernest Rutherford

(d) Niels Bohr

32: According to John Dalton's atomic theory, atoms are:

(a) Indivisible and indestructible particles

(b) Made up of protons, neutrons, and electrons

(c) Composed of positively charged protons and negatively charged electrons

(d) Always in motion around the nucleus

33: Who discovered the electron and proposed the plum pudding model of the atom?

(a) Ernest Rutherford

(b) J.J. Thomson

(c) Niels Bohr

(d) Marie Curie

34: Which scientist's experiment led to the discovery of the atomic nucleus?

(a) J.J. Thomson

(b) Niels Bohr

(c) Ernest Rutherford

(d) Max Planck

35: According to Bohr's model of the atom, electrons:

(a) Move in random orbits around the nucleus

(b) Move in circular orbits at fixed energy levels

(c) Move in continuous orbits with varying energy

(d) Move at the speed of light around the nucleus

36: The atomic number of an element is equal to the number of:

(a) Protons in the nucleus

(b) Electrons in the nucleus

(c) Protons and neutrons in the nucleus

(d) Neutrons in the nucleus

37: Who introduced the concept of energy levels or shells for electrons in the atom?

(a) John Dalton

(b) J.J. Thomson

(c) Niels Bohr

(d) Ernest Rutherford

38: What does the term 'isotope' refer to in atomic theory?

(a) Atoms with different numbers of protons and electrons

(b) Atoms with the same number of protons but different numbers of neutrons

(c) Atoms with the same number of neutrons but different numbers of protons
(d) Atoms with different numbers of electrons in their outermost shell

39. According to Dalton’s Atomic Theory, matter consists of indivisible _______

a) Molecules

b) Atoms

c) Ions

d) Mixtures

40. Atoms of different elements differ in mass.

a) True

b) False

41. What did Dalton’s Theory couldn’t explain?

a) gaseous volumes

b) conservation of mass

c) chemical philosophy

d) indivisible atoms

42. What is the name of Dalton’s publication?

a) A New system of atomic Philosophy

b) An old system of Chemical Philosophy

c) A New System of Chemical Philosophy

d) A New System of Chemical Prophecy

43. Which of the following may not be explained by Dalton’s atomic theory?

a) reason for combining atoms

b) conservation of mass
c) chemical philosophy

d) indivisible atoms

44. Law of conservation of mass isn’t explained in Dalton’s atomic theory.

a) True

b) False

45. What is 1 Dalton?

−27
a) a unified mass unit, 1.360539040×10 kg

−27
b) a unified mass unit, 1.640539040×10 kg

−27
c) a unified mass unit, 1.660539040×10 kg

−27
d) a unified mass unit, 1.660539040×10 kg

46. Could Dalton’s atomic theory explain the laws of chemical combinations?

a) No

b) Yes

c) Only a few

d) Except one

47. They are no limitations to Dalton’s atomic theory.

a) True

b) False

48. All atoms of a given element have identical __________ including identical _________

a) Properties, mass
b) Weight, volume

c) Volume, properties
d) Temperature, pressure

49. Which of the following models are not the same as Thomson Model of Atom?

a) plum pudding model

b) watermelon model

c) raisin pudding model

d) nuclear model

50. Which of the following statements you think is wrong regarding α particle scattering
effect?

a) α particles mostly move through the gold foil having zero deflection

b) A small fraction are deflected

c) One in Twenty Thousand turns 180°

d) The thickness of the gold foil is about 100μm

51. Chemical properties of an atom are dependent on a number of electrons in that

particular atom.

a) True
b) False

52. Pick out the isobar of 4018Ar.

a) 2412Mg

b) 5826Fe

c) 4019K
d) 6428Ni
53. Which of the following may be an incorrect statement regarding cathode ray
discharge tube?

a) Presence of negative charge in cathode rays

b) The magnetic field deflects these rays

c) It needs high voltage

d) Protons are present in cathode rays

54. Which of the following condition is suitable for cathode ray discharge tube?

a) Low pressure, high voltage

b) Low pressure, low voltage

c) High pressure, low voltage

d) High pressure, high voltage

55. Who did the oil drop experiment?

a) R. A. Millikan

b) J. J. Thomson

c) Rutherford
d) Galileo

56. When cathode rays strike zinc sulfide coating, what did it create?

a) bright spot

b) blue light

c) uv rays
d) white light

57. ___________ is the lightest and smallest particles that’s obtained from hydrogen(that
is a positive ion).
a) Electron

b) Proton

c) Neutron

d) Particle

58. What’s the mass of neutron in terms of electrons mass?

a) 1838 times of electron’s mass

b) 1/1838 times of electron’s mass

c) 1832 times of electron’s mass

d) 1/1832 times of electron’s mass

59.The below model of organization of electrons in atom is given by ___________

a) R. A. Millikan

b) J. J. Thomson

c) Rutherford
d) Galileo

60.Write 6354000000 in scientific notation.

a) 6.354 x 109

b) 6354 x 106
c) 0.64 x 1010

d) 6354000 x 103

61. _________ is referred to as the closeness of different measurements for the same
quantity.

a) Accuracy

b) Precision

c) Analysis

d) Dimension

62. A piece of iron is 5 inches long. How much would it be in centimeters?

a) 12.7 cm

b) 6.35 cm

c) 5 cm

d) 500 cm

63. How many significant figures does 0.057 have?

a) 2

b) 4

c) 3

d) 0

64. How many significant figures does 63180 have?

a) 5

b) 4
c) 1

d) 2

65. The exact value is 150m. A students record it as 140.1m in 1st turn and 140.8m in
the 2nd turn. Comment his/her recordings.

a) precise

b) accurate

c) neither precise nor accurate

d) both precise and accurate

66. The exact value is 150m. A students record it as 149.1m in 1st turn and 150.8m in
the 2nd turn. Comment his/her recordings.

a) precise

b) accurate

c) neither precise nor accurate

d) both precise and accurate

67. Multiply 1.2 and 3.91. Obtain the result as per the rules of significant figures.

a) 4.692

b) 4.69

c) 5

d) 4.7

68. How many significant figures are there in 60.6?

a) 4
b) 2

c) 3

d) 1

69. Which of the following scientists did not contribute to determining the structure of
the atom?

a. Thomson

b. Rutherford

c. Becquerel

d. Dalton

32 2-
70. The species that has the same number of electrons as 16S is:

35.5 33 3- 34 40
a. 17Cl b. 15P c. 16S d. 18Ar

71. Philosophy of changing substances into another form is called as _______

a) Physiology

b) Anatomy

c) Alchemy

d) Transformation

72. Which of the following may not be a physical property?

a) Odor

b) Color
c) Density

d) Composition

73. Candela is the S.I. unit of _____

a) Luminous intensity

b) Thermodynamic temperature

c) Amount of substance

d) Electric current

74. How many scientific fundamental quantities are given S.I. units?

a) 5

b) 7

c) 3

d) 9

75. What are the multiples for the prefixes yocto, atto respectively?

-24 -18
a) 10 , 10

b) 10-9, 10-15

c) 10-15, 10-24

d) 10-24, 10-21

76. What is the symbol of the amount of substance’s S.I. unit?

a) K

b) s
c) mol

d) kg

77. What is the difference in units between Kelvin and centigrade scales of temperature?

a) 212.15

b) 32

c) 298

d) 273.15

3
78. 1Litre = _______ m .

a) 1000

b) 0.001

c) 1

d) 10

79. What is the human body temperature in Fahrenheit?

a) 212

b) 98.6

c) 273.15

d) 32

80. What did Joseph Proust state regarding Law of Definite Proportions?

a) A given mixture always contains absolutely the same proportion of elements by

weight

b) A given compound always contains absolutely the same proportion of moles by

weight

c) A given compound always contains absolutely the same proportion of elements by

volume

d) A given compound always contains absolutely the same proportion of elements by

weight

81. The volumes of hydrogen & oxygen when combined bear a simple ratio of 2:1.This is
explained by ________

a) Law of Multiple Proportions

b) Avogadro’s Law

c) Law of Definite Proportion

d) Gay Lussac’s Law of Gaseous Volumes

82. Which of the following is not a law of chemical combination?

a) Law of Multiple Proportions

b) Avogadro’s Law

c) Law of Definite Proportion

d) Law of Conservation of volume

II. Fill in the blanks in the following statements:
(a) The number of protons in the nucleus of an atom is called its ______.
(b) The total number of protons and neutrons in the nucleus of an atom is called ______.
(c) An atom has atomic mass number 23 and atomic number 11. The atom has ______
electrons.
(d) An atom of an element has 11 protons, 11 electrons and 12 neutrons. The atomic
mass of the atom is ______.
(e) If the nucleus of an atom has atomic number 17 , mass number 37, and there are 17
electrons outside the nucleus, the number of neutrons in it is ______.
(f) Almost all the mass of an atom is concentrated in a small region of space called the
______.
(g) Cathode rays are a beam of fast-moving ______.
(h) The anode rays obtained from hydrogen gas consist of particles called ______.
(i) The maximum number of electrons that can be accommodated in L shell is ______.
(j) The maximum number of electrons that can go into the M shell is ______.
(k) The subatomic particle not present in a hydrogen atom is ______.
(l) The electron has ______ charge, the proton has ______ charge, and the neutron has
______ charge
(m) In water, the proportion of oxygen and hydrogen is _____ by mass.

(n) In a chemical reaction, the sum of the masses of the reactants and the products
remain unchanged. This is called _____

97. Name the shell of an atom which can accommodate a maximum of:
(a) 8 electrons? (b) 32 electrons?
(c) 2 electrons (d) 18 electrons
What is the maximum number of electrons which can be accommodated in the
following shell of an atom? a. K b. L c. M d. N
98. What is the maximum number of electrons which can be accommodated in the:

(a) Innermost shell of an atom?

(b) Outermost shell of an atom?

99.How many protons and neutrons are in the nucleus of each of the following atoms?
a. 2713Al b. 3216S c. 6430Zn d. 20782Pb
100. An element has the atomic number 12. How many electrons will be present in the K,
L and M energy shells of its atom?
101. Element X is toxic to humans in high concentration but essential to life at low
concentrations. It has four naturally occurring isotopes that contain 24 protons. Identify
element X and give the atomic symbol for the isotopes with 26, 28, 29, and 30 neutrons.
102. Naturally occurring boron consists of two isotopes, 10B and 11B, with the isotopic
masses 10.013 amu and 11.009 amu, respectively. The observed atomic mass of boron
is 10.811 amu. Calculate the abundance of each isotope
103. The two naturally occurring isotopes of lithium, lithium-6 and lithium-7, have
masses of 6.01512 amu and 7.01600 amu, respectively. Which of these two occurs in
greater abundance?
104. Name the scientist who gave:
(a) Law of conservation of mass
(b) Law of constant proportions
6. What is the absolute mass and charge as well as relative mass and charge of a
proton, electron and neutron?
7. Name the gas which produces anode rays consisting of protons in the discharge tube
experiment.

8. Which part of an atom was discovered by Rutherford’s alpha particle scattering

experiment?

9. ‘If 100 grams of pure water taken from different sources is decomposed by passing
electricity, 11 grams of hydrogen and 89 grams of oxygen are always obtained’. Which
chemical law is illustrated by this statement?

10. ‘If 100 grams of calcium carbonate(whether in the form of marble or chalk) are
decomposed completely, then 56 grams of calcium oxide and 44 grams of carbon
dioxide are obtained’. Which law of chemical combination is illustrated by this
statement?

Naturally occuring lithium consists of two isotopes whose atomic weights are 6.015 u and
7.016 u. The atomic weight of natural lithium is 6.491 u. The percentage by number of
atoms of each isotpe in natural lithium is and respectively.
1. Hydrogen has 3 isotopes. These are hydrogen with a mass number 1, 2 and 3.
i. Write the isotopic notation for these isotopes.
ii. How many protons, neutrons and electrons are present in each of these isotopes?
2. The mass number of chlorine is 35 and its atomic number is 17. Give the number of
its protons, electrons and neutrons.
3. What sub atomic particles are found in the central part of an atom nucleus?
4. What particles of an atom is determined the mass of an atom?
5. Write atleast four difference of electron, neutron & proton?
6. What are the atomic numbers and mass numbers of elements whose atoms are
made up of
a. 4 protons, 5 neutrons, 4 electrons;
b. 14 protons, 14 neutrons, 14 electrons;
c. 19 protons, 20 neutrons, 19 electrons?
7. How many protons, neutrons, and electrons are there in atoms of each of the
following elements?
a. Boron (atomic number 5, mass number 11)
b. Fluorine (atomic number 9, mass number 19)
c. Argon (atomic number 18, mass number 40)