## general science

### Chemistry MCQ Questions and Answers page - 1

1.
 What happens when a chemical bond is formed ? A Energy is always absorbed B Energy in always released C More energy is released than is absorbed D Energy is neither released nor absorbed Answer : A Explanation : Energy is always absorbed when a chemical bond is formed and energy is leleased when a chemical bond breaks.
2.
 “All the four quantum numbers of two electrons in an atom are not the same.” It is the law of – A Hund’s B Exclusion principle of pauli C Uncertainty principle of Hiesenberg D Avogadro’s law Answer : B Explanation : Exclusion principle of pauli states that  “All the four quantum numbers of two electrons in an atom are not the same.”
3.
 The atomic number of carbon is 6 and its atomic mass is 12. How many protons are there in the nucleus of carbon ? A 6 B 12 C 18 D Zero Answer : A Explanation :
4.
 Nucleus of an atom consists of A Proton B Neutron C Proton and neutron D Electron, proton and neutron Answer : C Explanation :
5.
 Isobars are lines joining places having equal A Rainfall B Pressure C Population D Height above sea – level Answer : B Explanation : Isobars are imaginary lines joining the places having equal values of pressure. For convenience all the pressure are converted to sea level. The spacing of isobars indicates the rate and direction of the pressure.
6.
 What is the element that is in the highest percentage in the composition of the earth ? A Silicon B Oxygen C Magnesium D Iron Answer : B Explanation :
7.
 Milk is a natural A Solution B Emulsion C Mixture D Suspension Answer : B Explanation :
8.
 Sea water can be purified by the process of A Distillation B Evaporation C Filtration D Fractional distillation Answer : A Explanation :
9.
 The residue left after extracting juice from sugar-beet and sugarcane is called A Molasses B Bagasse C Whey D Biomass Answer : B Explanation :
10.
 The isotope of Uranium used in atomic reactors is A U235 B U236 C U237 D U232 Answer : A Explanation :
11.
 The process of removing calcium and magnesium from hard water is known as A Sedimentation B Filtration C Flocculation D Water softening Answer : D Explanation :
12.
 The national Chemical Laboratory (India) is located in A Mumbai B Bangaluru C Hyderabad D Pune Answer : D Explanation :
13.
 Which of the following is not a nucleon ? A Proton B Neutron C Electron D Positron Answer : D Explanation :
14.
 What particles move around the nucleus of an atom and are negatively charged ? A Electrons B Protons C Positrons D Neutrons Answer : A Explanation :
15.
 The number of neutrons present in an element having mass number 226 and atomic number 88 is  : A 88 B 138 C 314 D 50 Answer : B Explanation :
16.
 An atom of an element has atomic number 17 and mass number 36. The number of neutrons in its nucleus is A 17 B 19 C 36 D 53 Answer : B Explanation :
17.
 Select the one which is not a mixture  : A Air B Gasoline C LPG D Distilled water Answer : D Explanation :
18.
 The total energy of revolving electron in an atom A Cannot  be negative B Can  have any value above zero C Can  never be positive D Will  always be positive Answer : C Explanation : The total energy of a revolving electron in any orbit is the sum of its kinetic and potential energies. Energy of an electron at infinite distance from the nucleus is zero. As an electron approaches the nucleus, the electron attraction increases and the energy of electron decreases and thus becomes negative. Thus, it can never be positive.
19.
 Conduction band electrons have more mobility than holes because they A Are lighter B Experience collision less frequently C Have negative charge D Need less energy to move them Answer : B Explanation :
20.
 The mass number of a nucleus is A Always less than its atomic number B Always more than its atomic number C Always equal to  its atomic number D Sometimes more and sometimes equal to its atomic number Answer : D Explanation :
21.
 The chemical behaviour of an atom depends upon A The number of protons in its nucleus B The number of neutrons in its nucleus C The number of electrons orbiting around the nucleus D The number of nucleons in the nucleus Answer : C Explanation :
22.
 The electronic configuration of an atom having atomic number ‘20’ is A 2, 8, 10 B 2, 6, 8, 4 C 2, 8, 8, 2 D 2, 10, 8 Answer : C Explanation :
23.
 A mixture of water and alcohol can be separated by A Filtration B Evaporation C Decantation D Distillation Answer : D Explanation :
24.
 The oxidation number of nickel in  K4[Ni(CN)4]  is A Zero B +4 C – 4 D +8 Answer : A Explanation :
25.
 The orientation of an atomic orbital is governed by A Principal quantum number B Magnetic quantum number C Spin quantum number D Azimuthal quantum number Answer : B Explanation :
26.
 The value of Avogadro Number is A 6.023 × 1022 B 6.023 × 1023 C 6.023 × 1024 D 6.023 × 1025 Answer : B Explanation :
27.
 The weight of 6.023 × 1022  atoms of carbon is A 12 gms B 120 gms C 1.2 gms D 0.12 gms Answer : A Explanation :
28.
 Suspension particles have the size between A 10-2 and 10-4 cm B 10-5 and 10-7 cm C 10-8 and 10-10 cm D 10-1 and 10-2 cm Answer : A Explanation :
29.
 The value of gas constant R in Ergs deg-1 mole-1 is A 8.314 × 107 B 8.341 × 107 C 8.413 × 107 D 4.183 × 107 Answer : A Explanation :
30.
 Rutherford’s scattering experiment proved the presence of A Atoms in all matter B Electrons in atoms C Neutrons in atoms D Nucleus in atoms Answer : D Explanation :
31.
 When a metal is heated in a flame, the electrons absorb energy and jump to higher energy state. On coming back to the lower energy state, they emit light which we can observe in A Raman spectra B Absorption spectra C Emission spectra D Fluorescence Answer : C Explanation :
32.
 Which one of the following has greatest mass ? A Electron B Proton C Neutron D Hydrogen nucleus Answer : C Explanation :
33.
 A colloidal system in which a liquid is dispersed in a liquid is called A Gel B Emulsion C Sol D Precipitate Answer : B Explanation :
34.
 Heavy water is so called because it contains A Heavy isotope of hydrogen B Heavy isotope of oxygen C Mole number of hydrogen atoms D Mole number of oxygen atoms Answer : A Explanation :
35.
 The nuclear particle having no mass and no charge, but only spin is A Proton B Neutrino C Meson D Electron Answer : B Explanation :
36.
 In a period from Li to F, ionisation potential A Cannot be predicted B Increases C Decreases D Remains same Answer : A Explanation :
37.
 Ionisation energy of nitrogen is greater than that of oxygen because nitrogen has A High bond dissociation energy B Smaller atomic radius C Stable half filled 2p sub level D High nuclear charge Answer : C Explanation :
38.
 ‘Atomic theory’ of matter was given by A Avogadro B Dalton C Newton D Pascal Answer : B Explanation :
39.
 Which among the following is a covalent compound ? A Calcium  chloride B Magnesium  fluoride C Sodium  chloride D Carbon  tetrachloride Answer : D Explanation :
40.
 Which of the following is the maximum number of electrons that can be present in M-shell ? A 2 B 8 C 18 D 32 Answer : C Explanation :
41.
 How many neutrons are there in   92U238  atom ? A 92 B 238 C 146 D 330 Answer : C Explanation :
42.
 When cathode rays strike a target of high atomic weight, they give rise to A $\alpha&space;-&space B $\beta&space;an C $X&space;-&space;rays$< D Positive rays Answer : C Explanation :
43.
 Atoms of different elements have A Same atomic number and same electronic configuration B Different atomic number and same electronic configuration C Different atomic number and different number of valence electrons D Same number of electrons and neutrons Answer : C Explanation :
44.
 Nucleons are regarded as composites sub-particles known as A Mesons B Quarks C Leptons D Photons Answer : B Explanation :
45.
 In the periodic table of elements, on moving from left to right across a period, the atomic radius A Decreases B Increases C Remains unchanged D Does not follow a definite pattern Answer : A Explanation :
46.
 Number of neutrons in an atom of hydrogen is A 1 B 0 C 2 D 3 Answer : B Explanation :
47.
 Who developed the model of atomic structure ? A Bohr and Rutherford B Volta C Alfred Nobel D faraday Answer : A Explanation :
48.
 When a bond is formed is formed between two atoms, the energy of the system will A Increase B Decrease C Remain the same D May increase or decrease Answer : C Explanation :
49.
 Muddy water is treated with alum in purification process, it is termed as : A Emulsification B Absorption C Adsorption D Coagulation Answer : D Explanation :
50.
 Which one of the following is also know as solution ? A A compound B A homogeneous mixture C A heterogeneous mixture D A suspension Answer : B Explanation :
51.
 A solution is A A homogeneous mixture of two or more substances B A solid dissolved in a liquid C A solid dissolved i water D A mixture of two liquids Answer : A Explanation :
52.
 Which of the following particles has the dual nature of particle wave ? A Electron B Meson C Proton D Neutron Answer : A Explanation :
53.
 Atoms having the same number of protons but different number of neutrons are called : A Isotopes B Cations C Higgs – boson D Anions Answer : A Explanation :
54.
 Iron filing can be separated from a heterogenous mixture using the technique of : A Sublimation B Magnetization C Sedimentation D Evaporation Answer : B Explanation :
55.
 The strongest oxidizing agent among the following is : A Chlorine B Iodine C Fluorine D Oxygen Answer : C Explanation :
56.
 The number of hydrogen bonds between guanine and cytosine in DNA is A 2 B 3 C 4 D 1 Answer : B Explanation :
57.
 J.J. Thomson’s proposed model of action is generally called  __________ model. A Cream and cake B Plum and pudding C Plum and cake D Cream and pudding Answer : B Explanation :
58.
 Atomic number of an atom gives the number of which of the following ? A Electrons B Protons C Neutrons D Neutrons and protons Answer : B Explanation :
59.
 In which of the following ions, the colour is not due to d-d transition ? A [Ti(H2O)6]3+ B CoF63- C MnO-4 D [Cu(NH3)4]2+ Answer : C Explanation :
60.
 Which one of the following has a maximum tendency to form M3 ion ? A N B Bi C P D As Answer : A Explanation :
61.
 The molecular mass of a gas is A Twice its vapour pressure B Equal to its vapour pressure C Half its vapour pressure D Not related to its vapour pressure Answer : A Explanation :
62.
 Chemical properties of isotopes A Must be same B Must be different C Need not be same D Need not be different Answer : A Explanation :
63.
 Two electrons in an orbital are differentiated by which of the following ? A Magnetic quantum number B Spin quantum number C Principal quantum number D Azimuthal quantum number Answer : B Explanation :
64.
 Isobars have  _______ . A Same mass numbers but different atomic numbers B Different mass numbers but same atomic numbers C Same mass and atomic numbers D Different mass and atomic numbers Answer : A Explanation :
65.
 Which among the following will be a negative ion ? A If it has more electrons than protons B If it has more electrons than neutrons C If it has more protons than electrons D If it has more protons than neutrons Answer : B Explanation :
66.
 The relation between bond length and bond energy is A Lower the bond energy, shorter the bond length B They are not related C Higher the bond energy, shorter the bond length D Higher the bond energy, longer the bond length Answer : C Explanation :
67.
 Electrons in the highest energy level of an atom are called  ________ . A Valence protons B Orbital protons C Valence electrons D Orbital electrons Answer : C Explanation :
68.
 What happens when one S and one P orbital are hybridized ? A We get three orbitals in a plane B We get two orbitals at 180 degrees C We get two mutually perpendicular orbitals D We get four orbitals directed tetrahedrally Answer : B Explanation :
69.
 Electrons move around the nucleus in  _________  motion. A Translator B Spin C Orbital D Vibrational Answer : C Explanation :
70.
 _________  character of a bond between two atoms is greater if the difference in their electro negativities is lesser. A Polar B Metallic C Ionic D Covalent Answer : D Explanation :
71.
 Two gaseous molecules can react only when they have same  _______ . A Free energy B Entropy C Energy D Orientation / steric factor Answer : D Explanation :
72.
 The subatomic particle that does not have any electric charge is a / an  _________ . A Electron B Proton C Neutron D All options are correct Answer : C Explanation :
73.
 What are the components of nucleus of an atom ? A Only protons B Protons and neutrons C Neutrons and electrons D Only neutrons Answer : B Explanation :
74.
 What is the mass of one mole of a substance in grams is called ? A Nuclear mass B Atomic mass C Molar mass D Molecular mass Answer : D Explanation :
75.
 What are isobars ? A Elements with same atomic number but different mass number B Elements with different atomic number but same mass number C Elements with different atomic number and different mass number D Elements with same atomic number and same mass number Answer : B Explanation :
76.
 Process of gaining electrons is known as  _________ . A Oxidation B Reduction C Radiation D Both Oxidation and Reduction Answer : B Explanation :
77.
 How many isotopes of Hydrogen element are there ? A 2 B 3 C 4 D None of the option is correct Answer : B Explanation :
78.
 Soil is an example of which of the following ? A Homog eneous mixture B Molecule C Compound D Heterogeneous mixture Answer : D Explanation :
79.
 An atom is  _________ . A The smallest particle of matter known B The smallest particle of a gas C The smallest indivisible particle of an element that can take part in a chemical change D Charged particle Answer : C Explanation :
80.
 Which of the following is NOT positively charged ? A Alpha particle B Proton C Helium nucleus D Electron Answer : D Explanation :
81.
 How many moles are present on 36 gm of water ? A 1 B 2 C 4 D 8 Answer : B Explanation :
82.
 What is the mass of 4 mole of aluminium atoms ? A 120 grams B 108 grams C 136 grams D 140 grams Answer : B Explanation :