Basic Concepts in Chemistry MCQs – I

1)According to the Stock system of nomenclature UO2SO4 is
a) dioxo uranium (VI) sulphate
b) dioxo uranium (IV) sulphate
c) dioxo uranium (II) sulphate
d) dioxo uranium (III) sulphate

2)The best method to identify trace elements is
a) neutron activation analysis
b) chromatogrphic method
c) n.m.r spectroscopy
d) radiocarbon dating

3)The number of significant figures in 0.0200 are
a) one
b) two
c) three
d) four

4)The number of significant figures in 0.0045 are
a) two
b) three
c) four
d) five

5)The greatest number of significant figures in 10500 are
a) three
b) four
c) five
d) can be any of these

6)The number of significant figures in are
a) three
b) four
c) five
d) can be any of these

7)The correctly reported answer of the addition of 40523, 2.3 and 6.24 will have significant figures
a) two
b) three
c) four
d) five

8)The correctly reported answer of the addition of 154.21, 6.142 and 23 will be
a) 183.352
b) 183.35
c) 183.4
d) 183

9)The correctly reported difference of 16.4215 and 6.01 will have significant figures equal to
a) three
b) four
c) five
d) six

10)After rounding off to three digits 1.235 and 1.225 we will have their answers respectively as
a) 1.23,1.22
b) 1.24,1.123
c) 1.23,1.23
d) 1.24,1.22

11)The actual product of 4.327 and 2.8 is 12.1156. The correctly reported answer will be
a) 12
b) 12.1
c) 12.12
d) 12.116

12)On dividing 0.46 by 15.374, the actual answer is 0.029236. The correct reported answer will be
a) 0.02
b) 0.029
c) 0.0292
d) 0.02924

13)Two students X and Y report the weight of the same substance as 5.0 g and 5.00 g respectively. Which of the following statements is correct?
a) Both are equally accurate
b) X is more accurate than Y
c) Y is more accurate than x
d) Both are inaccurate scientifically

14)Which of the following is incorrect about S.I units?
a)
b) Force in Newtons
c) Pressure in pascals
d)

15)Which of the following is correct?
a)
b)
c)
d)

16)The relationship between picometer (pm) and nanometer (nm) is
a) 1nm=1000pm
b) 1pm= 1000 nm
c) 1 pm = 100 nm
d) 1 pm = 100 pm

17)The nuclear cross section is measured in . It is equal to
a)
b)
c)
d)

18)In which of the following numbers are all zeros significant?
a) 0.00004
b) 0.0060
c) 20.000
d) 0.800

19)Planck’s constant has the dimensions of
a) force
b) work
c) angular momentum
d) torque

20)The units , nanometer, fermi, angstrom and attometre, arranged in decreasing order are expressed as
a) angstrom, nanometer, fermi, attometre
b) fermi, attometre, angstrom, nanometer
c) nanometer, angstrom, fermi, attometre
d) attometre, angstrom, fermi, nanometer

21)The value of Planck’s constant is . The numbers of significant figures in it is
a) six
b) five
c) three
d) thirty four

22)81.4 g sample of ethyl alcohol contains 0.002 g of water. The amount of pure ethyl alcohol (to the proper number of significant figures ) is
a) 81.398g
b) 81.40g
c) 81.4g
d) 81g

23)One torr is equal to
a) 1 cm of Hg
b) 1 atm pressure
c) 1 mm of Hg
d) 1 m of Hg

24)The Metric system was first introduced by
a) Archimedes
b) Galileo
c) The British Academy of Science
d) The French Academy of Science

25)The number of significant figures in are
a) three
b) infinite number
c) zero
d) one

26) Rydberg’s constant is . It can be expressed to three significant figures as
a)
b)
c)
d)

27) is the unit of
a) Momentum
b) Velocity
c) Pressure
d) Acceleration

28)The mass of a piece of paper is g and the mass of a solid substance along with the same piece of paper is 20.036 g. If the volume of the solid is , its density to the proper number of significant digits will be
a)
b)
c)
d)

29)Which of the following is not an element ?
a) Diamond
b) Graphite
c) Silica
d) Ozone

30)Which one of the following statements is correct?
a) all elements are homogenous
b) compounds made up of a number of elements are heterogeneous
c) a mixture is not always heterogeneous
d) Air is a heterogeneous mixture

31)The most abundant element in the earth’s crust is
a) Iron
b) Aluminium
c) Oxygen
d) Nitrogen

32)Which one of the following processes results in the formation of a new chemical compound?
a) dissolving common salt in water
b) heating water
c) heating a platinum rod
d) heating an iron rod

33)Which of the following statements is false ?
a) An element of a substance contains only one kind of atoms
b) A compound can be decomposed into its constituents
c) Milk is a homogenous mixture
d) All homogenous mixture are called solutions

34)Which one of the following is not a mixture ?
a) Iodized table salt
b) Gasoline
c) Liquefied petroleum gas ( L.P.G. )
d) Distilled water

35)Which one of the following mixtures cannot be separated by fractional distillation ?
a) Benzene + toluene
b) Acetone + Water
c) Acetone + Methyl alcohol
d) Glucose +Sucrose

36)A mixture of sand and naphthalene can be separated by
a) Washing with water
b) Magnetic separation
c) Sieving
d) Sublimation

37)Magnesium sulphate containing calcium sulphate as impurity can be separated by
a) distillation
b) crystallization
c) chromatography
d) fractional crystallisation

38)A mixture of can be separated by
a) distillation
b) crystallization
c) sublimation
d) adding acetic acid

39)A mixture that can be separated by sublimation method is
a)
b)
c)
d)

40)Chlorophyll extracted from green leaves can be separated into its components by
a) distillation
b) Filtration
c) chromatography
d) sublimation

41)10 g on heating leaves behind a residue weighing 5.6g. Carbon dioxide released into the atmosphere at STP will be
a) 2.24 L
b) 4.48 L
c) 1.12 L
d) 0.56 L

42)The atomic mass of an element is
a) The actual mass of one atom of the element.
b) The relative mass of an atom of the element
c) The weighted average relative mass of different isotopes of the element.
d) The same as the atomic number of the element

43)Nitrogen forms five stable oxides with oxygen of the formula . The formation of these oxides explains fully the
a) Law of definite proportions
b) Law of partial pressures
c) Law of multiple proportions
d) Law of reciprocal proportions.

44)Two metallic oxides contain 27.6% and 30.0 % oxygen respectively. If the formula of the first oxide is , that of the second will be
a) MO
b)
c)
d)

45)1L of combines with 3L of to form 2L of under the same conditions. This illustrates the
a) Law of constant composition
b) Law of multiple proportions
c) Law of reciprocal proportions
d)

46)12 g carbon combine with 64 g sulphur to form . 12 g carbon also combine with 32 g oxygen to form . 10 g sulphur combine with 10 g oxygen to form . These data illustrate the
a) law of multiple proportions
b) law of definite proportions
c) law of reciprocal proportions
d) law of gaseous volumes

47)Oxygen combines with two isotopes of carbon and to form two samples of carbon dioxide. The data illustrates
a) Law of conservation of mass
b) Law of multiple proportions
c) Law of reciprocal proportions
d) None of these

48)Which of the following does not represent 32 g of the substance?
a) one mole of oxygen atoms
b) one gram atom of sulphur
c)
d) Oxygen present in 2 moles of water

49)The isotopes of chlorine with mass numbers 35 and 37 exist in the ratio of
a) 1:1
b) 2:1
c) 3:1
d) 3:2

50)The correct value of Avogadro’s number is
a)
b)
c)
d)

51)Which one of the following statements is incorrect ?
a)
b)
c)
d)

52)5.6 litres of a gas N.T.P are found to have a mass of 11 g. The molecular mass of the gas is
a) 22
b) 44
c) 88
d) 32

53)The number of atoms of oxygen present in 10.6 g of will be
a)
b)
c)
d) 31.8

54)Which of the following contains the maximum number of molecules ?
a)
b)
c)
d)

55)The number of molecules present in a drop of water weighing 0.06g is approximately
a)
b)
c)
d)

56)Which of the following pairs contains an equal number of atoms ?
a) 11.2 cc of nitrogen and 0.015 g of nitric oxide
b) 22.4 litre of nitrous oxide and 22.4 litres of nitric acid
c)
d)

57)Which of the following has the maximum mass?
a) 0.1 g atom of carbon
b) 0.1 mol of ammonia
c)
d) 1120 cc of carbon dioxide

58)The total number of atoms present in 17 g of is
a)
b)
c)
d)

59)The mass of one atom of hydrogen is approximately
a) 1 g
b) 0.5 g
c)
d)

60)The mass of one molecule of water is approximately
a)
b)
c)
d)

61)Which of the following contains the same number of atoms as are present in 12 g of carbon ?
a) 28 g of iron (at mass of Fe = 56 )
b) 48 g of magnesium (at mass of Mg = 24)
c)
d) 14 g of carbon monoxide

62)The number of molecules present in of water is
a)
b)
c)
d)

63)The volume at N.T.P of 0.22 g of is not the same as that of
a) 0.01 g of hydrogen
b)
c)
d) 0.16 g of oxygen

64)0.6 g of carbon was burnt in the air to form . The number of molecules of introduced into the air will be
a)
b)
c)
d)

65)An electric bulb was filled with 100 cc of argon gas( At. Mass = 40) at and 1 atm pressure
a) 40000
b)
c)
d)

66)An evacuated observation balloon after filling with helium gas had an increase in weight equal to 2 g. The volume of the balloon at and 1 atm pressure must be, approximately
a) 2.8 L
b) 5.6 L
c) 11.2 L
d) 22.4 L

67)Equal volumes of different gases at any definite temperature and pressure have
a) Equal densities
b) Equal masses
c) Equal number of atoms
d) Equal number of molecules

68)The crystalline salt, on heating loses 59.6% of its weight. The formula of the crystalline salt is
a)
b)
c)
d) None of these

69)Which of the following represents the formula of a substance which contains about 26% nitrogen and 74% oxygen ?
a)
b) NO
c)
d)

70)How many atoms are present in a mole of ?
a)
b)
c)
d)

71)Which one of the following statements is incorrect?
a) Atoms of the same element may have different atomic weights.
b) Atoms can be created or destroyed
c) Half of an atom can also take part in a reaction
d) Elements can exist as atoms or molecules but compounds exist only as molecules.

72)An oxide of iodine (I= 127) contains 25.4 grams of iodine and 8 grams of oxygen. Its formula could be
a)
b)
c)
d)

73)One litre of a gas is at a pressure of mm of Hg at . How many molecules are present in the vessel ?
a)
b)
c)
d)

74)The normality of a in 60 mL solution is
a) 2N
b) 4N
c) N/2
d) N/4

75)The milliequivalents of in 60 mL solution is
a) 240
b) 480
c) 24
d) 48

76)A compound contains 69.5% oxygen and 30.5 % nitrogen and its molecular weight is 92 . The formula of the compound is
a)
b)
c)
d)

77)The number of molecules in one litre of a gas at S.T. P. is known as
a) Avogadro Number
b) Berzelius number
c)
d) Loschmidt number

78)280 ml of sulphur vapour at NTP weighs 3.2 g .The Species present in the sulphur vapour is
a) S
b)
c)
d)

79)A person adds 1.71 gram of sugar () in order to sweeten his tea. The number of carbon atoms added are (mol. mass of sugar = 342)
a)
b)
c)
d)

80)Which pair of species have the same percentage of carbon ?
a)
b)
c)
d)

81)The number of potassium atoms in 2 moles of potassium ferrocyanide is
a) 2
b)
c)
d)

82)The product of the atomic weight and specific heat of any element is constant which is approximately 6.4. This is known as
a)
b)
c)
d)

83)The approximate atomic weight of a metal having specific heat 0.32 is
a) 10
b) 20
c) 32
d) 64

84)0.1 g of a metal on reaction with dil. acid at S.T.P.liberates 34.2 ml hydrogen gas. The equivalent weight of the metal is
a) 32.7
b) 48.6
c) 64.2
d) 16.3

85)In the chemical scale , the relative mass of the isotopic mixture of oxygen atoms is assumed to be equal to
a) 16.002
b) 16.00
c) 17.00
d) 11.00

86)The weight of two elements which combine with one another are in the ratio of their
a) atomic weight
b) molecular weight
c) gram mole
d) equivalent weight

87)The vapor density of a metal chloride is 66. Its oxide contains 53% metal. The atomic weight of the metal is
a) 21
b) 54
c) 27
d) 2

88)One gram of hydrogen is found to combine with 80 g of bromine. One gram of a metal (valency=2) combines with 4 gm of bromine. The equivalent weight of the metal is
a) 10
b) 20
c) 40
d) 80

89)When 100 ml of 1 M NaOH solution and 10 ml of solution are mixed together, the resulting solution will be
a) alkaline
b) acidic
c) strongly acidic
d) neutral

90)The percentage of copper and oxygen in samples of CuO obtained by different methods were found to be the same. This illustrates the law of
a) constant proportions
b) conservation of mass
c) multiple proportions
d) reciprocal proportions

91)If molecules are removed from 200 mg of , then the number of moles of left are
a)
b)
c)
d)

92)A compound contains 38.8% C, 16.0% H and 45.2% N. The formula of the compound would be
a)
b)
c)
d)

93)What is the normality of 1M solution of ?
a) 0.5
b) 1N
c) 2N
d) 3N

94)How much water should be added to 200 c.c. of semi normal solution of NaOH to make it exactly deci normal?
a) 200cc
b) 400cc
c) 800cc
d) 600cc

95)The number of molecules in 100 ml each of , and
a)
b)
c) the same
d)

96)Two samples of lead oxide were separately reduced to metallic lead by heating in a current of hydrogen. The weight of lead from one sample was half that obtained from the other. The data illustrates the
a) Law of reciprocal proportions.
b) Law of constant proportions
c) Law of multiple proportions
d) Law of equivalent proportions.

97)What is the concentration of nitrate ions, if equal volume of and 0.1 M NaCl are mixed together?
a) 0.1 M
b) 0.2 M
c) 0.05 M
d) 0.25 M

98)One part of an element A combines with two parts of another element B. Six parts of the element C combine with four parts of the element B. If A and C combine together the ratio of their weights will be governed by the
a) law of definite proportions
b) law of multiple proportions
c) law of reciprocal proportions
d) law of conservation of mass.

99)1.520 g of the hydroxide of a metal on ignition gave 0.995 g of oxide. The equivalent weight of the metal is
a) 1.520
b) 0.995
c) 19.00
d) 9.00

100)A solution of was titrated with solution in an acidic medium. The amount of used will be <I
a) 5 ml of 0.1 M
b) 10 ml of 0.1 M
c) 10 ml of 0.5 M
d) 10 ml of 0.02 M

Answers

Continued Questions 101-200 – Click Here

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