CBSE Class 9 Science Structure of Atom MCQs

Answer: C

Question:  The valence electrons of an element are reponsible for
(A) Physical properties of an element
(B) Chemical properties of an element
(C) Both the properties
(D) None of these 

Answer: B

Question: An element has electronic configuration 2,8,4 it will be classified as
(A) Metal
(B) Non metal
(C) Metalloid
(D) None of these

Answer: C

Question: Isotopes of an element do not have
(A) Same number of element
(B) Same physical properties
(C) Same chemical properties
(D) Same elecrical charge on the nucleus

Answer: B

Question: Amongst element X (2,8,6) and (2,8,8) which is more reactive and why ?
(A) X because it is a metal
(B) Y because it is non metal
(C) X because it has 6 valence electrons
(D) Y because it is gas 

Answer: C

Question: Cathode rays have
(A) Mass only
(B) Charge only
(C) Both mass and charge
(D) Neither mass nor charge

Answer: C

Question: Which of these is a pairs isobar ?
(A) 6C12, 8O16
(B) 6C13, 6C14
(C) 20Ca40, 18Ar40
(D) None of these

Answer: C

Question: 7N15 and 8O16 are a pair of
(A) Isotopes
(B) Isobars
(C) Isotones
(D) None of these 

Answer: C

Question: The nucleus of the hydrogen atom is called as
(A) Neutron
(B) Electron
(C) Proton
(D) Nucleons 

Answer: C

Question: The e/m value for cathode rays
(A) varies with the nature of the gas
(B) does not vary with the nature of gas
(C) could not be determinde by J.J. Thomson
(D) Both (B) & (C) are correct 

Answer: B

Question: Cathode raysget deflected in a electric field towards
(A) Positive plate
(B) Negative Plate
(C) No deflection takes place
(D) First towards negative plate and then towards positive plate 

Answer: A

Question: Isotopes differ in
(A) No. of electrons
(B) No. of protons
(C) No. of neutrons
(D) Chemical reactivity 

Answer: C

Question: The atomic number of an element ‘y’ is 20. The electronic configuration of the ion having inert gas configuration is
(A) 2,8,10
(B) 2,18
(C) 2,10,8
(D) 2,8,8 

Answer: D

Question: Which amonght the following statement is true?
(A) a rays are cathode rays
(B) Electrons make up the cathode rays
(C) Protons make up the cathode rays
(D) Electron magnetic radiation make up the cathode rays

Answer: B

Question: The isotope of hydrogen that contains the same numer of protons and neutrons in its nucleus is called
(A) Protium
(B) Deutrium
(C) Tritium
(D) None of these 

Answer: B

Question: a particle is emitted by 92X238 during redioactivity. The new specie y should be :
(A) 90Y234
(B) 90Y238
(C) 92Y234
(D) 94Y234 

Answer: A

Question: When an a-particle is emitted
(A) Element moves 2 places to the right in the periodic table
(B) Element moves one place to the left
(C) Element moves 2 places to the left in the periodic table
(D) Elements maintains its position

Answer: C

Question: If the nuclide of actinium 89Ac228, emits b particle, the daughter nuclide will be
(A) 88Ra228
(B) 90Th228
(C) 87Fr224
(D) 90Th229

Answer: B

Question: The relative atomic masses of many elements are not whole numbers because
(A) They can’t be determined very accurately
(B) The atoms ionize during the determination
(C) of the existence of isotopes
(D) of the presence of impurities

Answer: C

Question: The energy associated with an orbit
(a) increases with his distance from the nucleus
(b) decreases with increase in the distance from nucleus
(c) remains constant whatever may be the distance
(d) none of these   

Answer: A

Question:  The orbits are numbered by
(a) 100, 200, 300....
(b) 10, 20, 30....
(c) 1, 2, 3, 4....
 (d) 5, 10, 15....

Answer: C

Question:  The shells or orbits are denoted by
(a) K, L, M, N,.....
(b) a, b, c, d,....
(c) A, B, C, d,....
(d) V, W, X, Y, Z,....

Answer: A

Question:  The shell which has two electrons is
(a) first shell
(b) second shell
(c) third shell
(d) fourth shell

Answer: A

Question:  Maximum number of electrons, the third shell can accommodate is
(a) 32
(b) 2
(c) 8 
(d) 18 

Answer: D

Question:  In general, the nth shell can accommodate_____ electrons where ‘n’ stands for number of the shell.
(a) 3n^₂ 
(b) 2n²
(c) n² 
(d) 2n 

Answer: B

Question:  The distribution of _____ in various orbits of an atom is called electronic configuration of element
(a) neutrons
(b) protons
(c) electrons
(d) all of these 

Answer: C

Question:  The electronic configuration of oxygen
(a) 2, 7
(b) 2, 6
(c) 2, 4, 2
(d) 4, 4 

Answer: B

Question:  2, 8,1 is the electronic configuration of
(a) lithium
(b) potassium
(c) helium
(d) sodium 

Answer: D

Question:  Number of electrons in the outermost shell of carbon is
(a) 4
(b) 6
(c) 3
(d) 8 

Answer: A

Question:  Total number of electrons in an atom of nitrogen is
(a) 9
(b) 6
(c) 8
(d) 7 

Answer: D

Question:  The noble gases from the following are
(a) O_2, N₂, H₂ 
(b) Cl, F, Br
(c) He, Ne, Ar
(d) Na, K, Ca

Answer: C

Question:  Noble gases do not react with other elements to form compounds because
(a) they are unstable
(b) they are gases
(c) they are stable
(d) they are already compounds

Answer: C

Question:  In a chemical reaction, ___________ participate.
(a) valence electrons
(b) all electrons of the atom
(c) protons
(d) electrons and protons

Answer: A

Question: The valency of an element is its
(a) electronic configuration
(b) combining capacity
(c) atomic number
(d) mass number

Answer: A

Question:  Atoms combine to attain stable configuration by
(a) sharing electrons
(b) sharing, accepting or donating electrons
(c) donating electrons
(d) accepting electrons

Answer: B

Question:  A chlorine atom has ____ protons, _____ electrons and _____ neutrons.
(a) 18, 17, 18
(b) 17, 18, 18
(c) 17, 17, 18
(d) 17, 17, 17 

Answer: C

Question:  The number of electrons shared between two oxygen atoms is
(a) 2
(b) 1
(c) 2
(d) 4 

Answer: D

Question: . The number of electrons shared by each chlorine atom to form a molecule is
(a) 2
(b) 1
(c) 3
(d) 7 

Answer: B

Question:  In a CO₂ molecule, the total number of electrons shared between a carbon and two oxygen atoms are
(a) 8
(b) 4
(c) 2
(d) 6

Answer: B

Question:  In the formation of NaCl, sodium atom
(a) receives an electron
(b) shares an electron
(c) does not react
(d) donates an electron 

Answer: D

Question:  Sodium ion (Na+) has ____ number of electrons
(a) 10
(b) 12
(c) 11
(d) 13 

Answer: A

Question:  When chlorine atom becomes chloride ion it
(a) loses an electron gains an electron
(b) gains an electron
(c) electrostatic force
(d) magnetic force

Answer: B

Question:  Sodium and chlorine atoms are held together in NaCl by

(a) electromagnetic force
(b) gravitational force

(c) electrostatic force
(d) magnetic force 

 

Answer: C

 

Question:  An atom that becomes charged by gaining or losing an electron is called

(a) cation
(b) anion

(c) ion
(d) electron

 

Answer: C

 

Question:  Compound formed by sharing electrons is called

(a) ionic compound
(b) electrovalent compound

(c) covalent compound
(d) coordinate compound

 

Answer: C

 

Question:  Cations are carry

(a) both positive and negative charges
(b) neutral charge

(c) negative charge
(d) positive charge

 

Answer: D

 

Question:  Mg →Mg²⁺ ______

(a) 2 electrons
(b) 1 electrons

(c) no electrons
(d) 2 protons 

 

Answer: A

 

Question:  An aluminium ion carries _____ units of positive charge

(a) 2
(b) 3

(c) 1
(d) 4

 

Answer: B

 

Question: Question:  Oxygen atom becomes an oxide ion by

(a) losing two electrons
(b) gaining two electrons

(c) gaining one electron
(d) losing one electron

 

Answer: B

 

Question: The scientist who put forward the atomic theory in 1808 was

(a) Dalton
(b) Lavoiser

(c) Galileo
(d) Thomson 

 

Answer: A

 

Question: According to the atomic theory

(a) matter is not created but can be destroyed in a chemical reaction.

(b) matter is neither created nor destroyed in a chemical reaction

(c) matter is created but not destroyed in a chemical reaction

(d) matter can be created and destroyed in a chemical reaction 

 

 Answer: B

 

Question: Which of the following statement is true?

(a) Elements combine in fixed proportion by volume to form compounds

(b) Elements combine in fixed proportions by weights to form compounds

(c) elements combine in fixed proportion by mass to form compounds

(d) None of these

 

Answer: C

 

Question: The scientist who measured the mass and charge of an electron was

(a) Goldstein
(b) Rutherford

(c) Dalton
(d) Thomson

 

Answer: D

 

Question: The mass of an electron is

(a) 1837 times the mass of proton
(b)1/1837 th times the mass of hydrogen atom

(c)1/1831 th times the mass of oxygen atom
(d)1/1837 th times the mass of carbon atom

 

Answer: B

 

Question: The mass of proton is about the same as that of

(a) carbon atom
(b) an electron

(c) hydrogen ion
(d) oxygen atom 

 

Answer: C

 

Question: Rutherford directed a stream of _____ on a thin gold leaf in the scattering experiment

(a) alpha particles
(b) beta particles

(c) gamma particles
(d) X-rays 

 

Answer: A

 

Question: Based on his experiments, Rutherford concluded that the positive charge of an atom is

(a) spread all over the atom
(b) revolves around the atom in orbits

(c) exists in the empty space
(d) present in the nucleus

 

Answer: D

 

Question: Atomic number of an atom is the

(a) number of protons + number of neutrons
(b) number of neutrons

(c) number of electrons + number of protons
(d) number of protons

 

Answer: D

 

Question: Atomic number of an element is denoted by

(a) X
(b) A

(c) Z
(d) N

 

Answer: C

 

Question: In a neutral atom, the number of protons is equal to

(a) half the number of electrons
(b) number of electrons

(c) number of neutrons
(d) number of neutrons + number of electrons

 

Answer: B

 

Question: Atomic mass of an element is the number of times by which the mass of its atom is greater than

(a) 1/12 th mass of carbon atom
(b) 1/12 th mass of hydrogen atom

(c) 1/12 th mass of oxygen atom
(d) 1/12 th mass of helium atom 

 

Answer: A

 

Question: Neutrons were discovered by

(a) Joseph Thomson
(b) James Chadwick

(c) Ernest Rutherford
(d) John Dalton 

 

Answer: B

 

Question: Mass of neutron is equal to

(a) that of an electron
(b) half the mass of an electron

(c) the mass of a proton
(d) half the mass of a proton

 

Answer: C

 

Question: The mass number of an element is the sum of the numbers of

(a) protons and electrons
(b) electrons and neutrons

(c) protons, electrons and neutrons
(d) protons and neutrons 

 

Answer: D

 

Question: The mass number of an element is denoted by

(a) A
(b) Z

(c) X
(d) N 

 

Answer: A

 

Question: The element with the same atomic and mass number is

(a) oxygen
(b) hydrogen

(c) helium
(d) carbon

 

Answer: B

 

Question: In the periodic table, the elements are arranged in the

(a) increasing order of atomic mass
(b) decreasing order of atomic number

(c) alphabetical order
(d) increasing order of atomic number

 

Answer: D

 

Question: The symbol of the element sodium is

(a) Si
(b) S

(c) Na
(d) N

 

Answer: C

 

Question: K is the symbol of

(a) potassium
(b) calcium

(c) krypton
(d) aluminium

 

Answer: A

 

Question: The element with the same atomic number and mass number is

(a) Oxygen
(b) Hydrogen

(c) Helium
(d) Carbon

 

Answer: B

 

Question: The mass of an electron is

(a) 1837 times the mass of proton
(b) 1/1837th times the mass of oxygen atom

(c) 1/1837th times the mass of carbon atom
(d) 1/1837th times the mass of hydrogen atom 

 

Answer: D

 

Question: The scientist who put forward the atomic theory in 1808 was

(a) Dalton
(b) Lavoiser

(c) Galileo
(d) Thomson

 

Answer: B

 

Question: The mass number of an element is the sum of the number of

(a) Proton and electron
(b) Electron and neutrons

(c) Protons, electrons and neutrons
(d) Protons and neutrons

 

Answer: A

 

Question: Rutherford directed a stream of __________on a thin Gold leaf in the scattering experiment

(a) Alpha particle
(b) Beta particle

(c) Gamma particle
(d) X-rays

 

Answer: D

 

Question: In the periodic table, the elements are arranged in the

(a) Increasing order of atomic mass
(b) Decreasing order of atomic number

(c) Alphabetical order
(d) Increasing order of atomic number 

 

Answer: A

 

Question: In a neutral atom, the number of protons is equal to

(a) Number of electrons
(b) Half the number of electrons

(c) Number of neutrons
(d) Number of electrons and neutrons

 

Answer: C

 

Question: The mass number of an element is denoted by

(a) A
(b) Z

(c) X
(d) N 

 

Answer: D

 

Question: The e/m ratio of an electron for all types of substances is

(a) constant
(b) less than one

(c) greater than one
(d) zero

 

Answer: A

 

Question: A proton is identical to

(a) the nucleus of berellium
(b) the nucleus of helium

(c) a molecule of a hydrogen
(d) an atom of hydrogen

 

Answer: A

 

Question: An particle is

(a) a hydrogen molecule
(b) a helium nucleus

(c) an electron
(d) a proton 

 

Answer: A

 

Question: The atomic number of an element is determined by

(a) the number of electrons in one atom
(b) the number of neutrons in one atom

(c) the valency of the element
(d) the number of protons in one atom

 

Answer: D

 

Question: The value of e/m of an electron was measured by

(a) Millikan
(b) J.J. Thomson

(c) Dalton
(d) Rutherford 

 

Answer: B  

 

Question: The atomic number of an element is 11 and its mass number is 23. The respective number of electrons, protons and neutrons in this atom will be

(a) 11, 11, 12
(b) 11, 12, 11

(c) 12, 11, 11
(d) 23, 11, 23 

 

Answer: D

 

Question: The number of electrons in the outer shell of the most stable or inert atoms is

(a) 1
(b) 4

(c) 6
(d) 8

 

Answer: A

 

Question: Which of the following pairs are isotopes?

(a) Oxygen and ozone
(b) Ice and steam

(c) Nitric oxide and nitrogen dioxide
(d) Hydrogen and deuterium 

 

Answer: A

 

Question: An atom which has a mass number of 14 and has 8 neutrons is an

(a) isotope of oxygen
(b) isobar of oxygen

(c) isotope of carbon
(d) isobar of carbon

 

Answer: D

 

Question: Which of the following has an equal number of neutrons and protons?

(a) Hydrogen
(b) Deuterium

(c) Fluorine
(d) Chlorine 

 

Answer: D

 

Question: Members of which of the following have similar chemical properties?

(a) Isotope
(b) Isobars

(c) Allotropes
(d) Both isotopes and allotropes

 

Answer: C

 

Question: An atom of an element has 26 electrons and has a mass number 56. The nucleus of this atom contains ______ neutrons

(a) 26
(b) 36

(c) 30
 (d) 56

 

Answer: B

 

Question: For an element with atomic number 19, the 19th electron will occupy

(a) L-shell
(b) M-shell

(c) N-shell
(d) K-shell

 

Answer: A

 

Question: The number of electrons in an element with atomic number X and atomic mass Y will be

(a) X – Y
(b) Y – X

(c) X + Y
(d) X

 

Answer: C

 

Question: A natural phenomenon that supports the experimental conclusion that atoms are divisible is

(a) allotropy
(b) radioactivity

(c) cracking
(d) none of these

 

Answer: C

 

Question: The number of valence electrons determines:
(a) Chemical properties of elements
(b) Physical properties of elements
(c) Both physical and chemical properties of elements
(d) Neither physical nor chemical properties of elements

 

Answer: A

 

Question: Cathode rays have :
(a) Charge only
(b) Mass only
(c) Charge as well as mass
(d) Neither charge nor mass

 

Answer: B

 

Question: Which of the following are isobars: 18Ar⁴⁰, 19 K³⁹ ,20 Ca⁴⁰, 19[K⁺]³⁹
(a) 18 Ar⁴⁰,20 Ca⁴⁰,
(b) 19 K³⁹ , 19+[K⁺]³⁹
(c) 18 Ar⁴⁰,19 K³⁹
(d) 18 Ar⁴⁰,19 K³⁹ ,20 Ca⁴⁰

 

Answer: A

Question: Which of the following are isotopes: 1 ¹ H, 1 ²D,1 ³ T,1 ¹ H+
(a) 1 ¹ H, 1 ²D,1 ³ T
(b) 1 ¹ H, 1 ¹ H+
(c) 1 ¹ H, 1 ²D,1 ¹ H+
(d) 1 ¹ H, 1 ³ T,1 ¹ H+

 

Answer: A

Question: The electronic configuration of Cl- ion is:
(a) 2,8,8
(b) 2,8,7
(c) 2,8,6
(d) 2,8,8,1

 

Answer: A

Question: Which of the following does not have one electron in its valance shell
(a) Na
(b) Ca
(c) Li
(d) H

 

Answer: B

Question: Which of the following does not have 8 valence electrons:
(a) He
(b) Ne
(c) Ar
(d) Cl

 

Answer: A

 

Question: How many electrons, protons and neutrons are present in X+, if atomic number of X is 19 and its mass number is 39
(a) E=19, P=19, N= 20
(b) E=18, P=19, N= 20
(c) E=18, P=19, N= 19
(d) E=19, P=20, N= 20

 

Answer: A

Question: Which of the following statements does not belong to Bohrs model?
(a) The electrons radiate energy during revolution due to force of attraction between nucleus and electrons
(b) Energy of the electrons in the orbit is quantized
(c) The electrons in the orbit nearest to the nucleus is the lowest energy
(d) Electrons revolve around the nucleus in different orbits having fixed energies

 

Answer: A

Question: When a gold foil is bombarded by a beam of α particle, only a few of them get deflected whereas most go straight undeflecte This is because
(a) The volume of nucleus is much smaller than that of the atom
(b) The force of attraction exerted on α particles by the electrons is insufficient
(c) The force of repulsion acting on the fast moving α particles is very small
(d) The neutrons have no effect on α particles

 

Answer: A

 

More Questions...........................

Question: The highest value of e/m ratio for anode rays is observed when the discharge tube is filled with:
(a) N₂
(b) H₂
(c) He
(d) Ar

 

Answer: B

Question: Which of the following statement is correct about proton?
(a) It is an ionized Hydrogen atom
(b) It is the nucleus of deuterium
(c) It is an ionized hydrogen molecule
(d) It is an α particle with unit positive charge

 

Answer: A

 

Question. The ion of an element has 3 positive charges. Mass number of the atom 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

Answer : B

Question: Na+ has 12 neutrons and 10 electrons. Which of the following statements is correct?
(a) Na+ has atomic number 11 and mass number 23.
(b) Na+ has atomic number 10 and mass number 22.
(c) Na+ has atomic number 10 and mass number 23.
(d) Na+ has atomic number 11 and mass number 22.

 

Answer: A

Question: Composition of the nuclei of two atomic species are given:

 

 

                                               X                                                                  Y
P                                             

                                               7                                                                   8

 

N                                             9                                                                   8

(a) 16,16; 1sobars
(b) 16,16; isotopes
(c) 17,15; isotopes
(d) 17,15; isotopes

 

Answer: A

Question: The electronic configuration of Cl(17) is:
(a) 2,8,7
(b) 2,2, 8,5
(c) 2,8,2,5
(d) 2,2,5,8

 

Answer: A

Question: Which of the following are positively charged ions:

Atoms      Protons         Electrons           Neutrons
   A            17               17                     18
   

  B             12               10                     12
   

  C             16               17                     20
 

  D             1
   

  E             18              18                     22
   

  F             10              10                     10

 

(a) B and D
(b) A and B
(c) C and D
(d) D and F

 

Answer: A

Question: If K, L, M, N shells of an atom are full, the total number of electrons in the atom are:
(a) 60
(b) 26
(c) 42
(d) 36

 

Answer: A

Question: Which of the following is correct?
Column 1                  Column 2
 

A. Electrons         i. Positive charge
B. Protons           ii. No charge
C. Neutrons        iii. Negative charge
(a) A-iii, B-i, C-ii
(b) A-iii, B-ii, C-i
(c) A-ii, B-iii, C-i
(d) A-ii, B-i, C-iii

 

Answer: A

Question: A student weighs 30kg. Suppose his body is entirely made of electrons. How any electrons are there in his body? Mass of an electron= 9.1X10-31kg
(a) 3.29 X10³¹
(b) 3.29 X10³⁰
(c) 3.29 X10²³
(d) 3.29 X10³²

 

Answer: A

Question: The charge/ mass ratio of electron:
(a) Remains constant
(b) Depends on the nature of the electrodes
(c) Depends upon nature of the gas
(d) Depends on both nature of the gas and nature of the electrode

 

Answer: A

 

Question: Who discovered the electron?
(a) Rutherford
(b) Chadwick
(c) Thomson
(d) Goldstein

 

Answer : C

Question: The fluorescence on the walls of discharge tube is due to:
(a) Cathode rays
(b) Anode rays
(c) Canal rays
(d) None of the above

 

Answer : A

Question: The isotope used to remove the brain tumours and treatment of cancer is
(a) U-235
(b) Na-24
(c) Iodine
(d) C0-60

 

Answer : D

Question: The nucleons are
(a) Protons and electrons
(b) Neutrons and electrons
(c) Protons and neutrons
(d) None of these

 

Answer : C

Question: How many electrons in a Hydrogen (H) atom:
(a) One
(b) Two
(c) Three
(d) Four

 

Answer : A

Question: The atomic number of the element with maximum number of unpaired electrons is:
(a) 23
(b) 33
(c) 15
(d) 26

Answer : D

Question: 13Al27 is a stable isotope. 13Al29 is expected to disintegrate by:
a.α emission
(b) β emission
(c) Positron emission
(d) Proton emission

 

Answer : B

Question: The atomic number of an element having mass number 23 and number of neutron 12 is ________.
(a) 23
(b) 11
(c) 12
(d) 35

Answer: B

Question: Isotopes are
(a) atoms of the same element
(b) atoms of different elements
(c) molecules of the same element
(d) radicals of the same element

 

Answer : A

 

Question: What property of an element determines its chemical behaviour?
(a) Size of an element
(b) Valency of an element
(c) Molar mass of the element
(d) None of these

 

Answer. B

Question: What property of an element determines its chemical behaviour?
(a) Size of an element
(b) Valency of an element
(c) Molar mass of the element
(d) None of these 

 

Answer : B

 

Question: Which of the following isotope is used in the treatment of blood cancer?
(a) P-32
(b) I-131
(c) Co-60
(d) any of these

 

Answer : A

Question: When alpha-particles are sent through a thin metal foil, most of them go straight through the foil because
(a) alpha-particles are positively charged
(b) alpha-particles are much smaller than electrons
(c) alpha-particles move with low velocity
(d) most part of the atom is empty

 

Answer : D

Question: The electronic configuration of an atom with atomic number 19 is:
(a) 2, 8, 8, 1
(b) 1, 2, 2, 8
(c) 2, 8, 9
(d) 2, 10, 7

 

Answer : A 

 

Question: The charge/ mass ratio of electron:

(a) Depends on the nature of the electrodes

(b) Depends upon nature of the gas
(c) Remains constant

(d) Depends on both nature of the gas and nature of the electrodea

 

Answer : c

 

Question: A student weighs 30kg. Suppose his body is entirely made of electrons. How any electrons are there in his body? Mass of an electron= 9.1X10^-31kg

(a) 3.29 X10³¹

(b) 3.29 X10³⁰

(c) 3.29 X10²³

(d) 3.29 X10³²

 

Answer : A

 

Question: Which of the following is correct?

   Column 1             Column2

(a) Electrons      i. Positive charge

(b) Protons        ii. No charge

(c) Neutrons     iii. Negative charge

(a) A-iii, B-ii, C-i

(b) A-iii, B-i, C-ii

(c) A-ii, B-iii, C-i

(d) A-ii, B-i, C-iii

 

Answer : C

 

Question: If K, L, M, N shells of an atom are full, the total number of electrons in the atom are:

(a) 60
(b) 26
(c) 42
(d) 36

 

Answer : A

 

Question: Which of the following are positively charged ions:

 

(a) A and B

(b) C and D

(c) B and D

(d) D and F 

 

Answer : C

 

Question: The electronic configuration of Cl(17) is:

(a) 2,8,7

(b) 2,2, 8,5

(c) 2,8,2,5

(d) 2,2,5,8 

 

Answer : A

 

Question: Composition of the nuclei of two atomic species are given: 

The mass number of x and Y and their relation is

(a) 16,16; isotopes

(b) 17,15; isotopes

(c) 17,15; isotopes

(d) 16,16; 1sobars

 

Answer : D

 

Question: Na⁺ has 12 neutrons and 10 electrons. Which of the following statements is correct?

(a) Na⁺ has atomic number 10 and mass number 22.

(b) Na⁺ has atomic number 11 and mass number 23.

(c) Na⁺ has atomic number 10 and mass number 23.

(d) Na⁺ has atomic number 11 and mass number 22.

 

Answer : B

 

Question: Which of the following statement is correct about proton?

(a) It is the nucleus of deuterium

(b) It is an ionized hydrogen molecule

(c) It is an ionized Hydrogen atom

(d) It is an α particle with unit positive charge

 

Answer : C

 

Question: The highest value of e/m ratio for anode rays is observed when the discharge tube is filled with:

(a) N₂ 
(b) H₂ 
(c) He
(d) Ar

 

Answer : B

 

Question: When a gold foil is bombarded by a beam of α particle, only a few of them get deflected whereas most go straight undeflecte(d) This is because

(a) The force of attraction exerted on α particles by the electrons is insufficient

(b) The volume of nucleus is much smaller than that of the atom

(c) The force of repulsion acting on the fast moving α particles is very small

(d) The neutrons have no effect on α particles 

 

Answer : B

 

Question: Which of the following statements does not belong to Bohr’s model?

(a) Energy of the electrons in the orbit is quantized

(b) The electrons in the orbit nearest to the nucleus is the lowest energy

(c) Electrons revolve around the nucleus in different orbits having fixed energies

(d) The electrons radiate energy during revolution due to force of attraction between nucleus and electrons

 

Answer : D

 

Question: How many electrons, protons and neutrons are present in X⁺, if atomic number of X is 19 and its mass number is 39

(a) E=19, P=19, N= 20

(b) E=18, P=19, N= 20

(c) E=18, P=19, N= 19

(d) E=19, P=20, N= 20

 

Answer : A

 

Question: Which of the following does not have 8 valence electrons:

(a) He
(b) Ne
(c) Ar
(d) Cl^-

 

Answer : A

 

Question: Which of the following does not have one electron in its valance shell

(a) Na
(b) Li
(c) H
(d) Ca 

 

Answer : D

 

Question: The electronic configuration of Cl^- ion is:

(a) 2,8,7

(b) 2,8,8

(c) 2,8,6

(d) 2,8,8,1

 

Answer : 17 A 

 

 Answer:  18 C

 

Question: Cathode rays have :

(a) Charge only

(b) Mass only

(c) Charge as well as mass

(d) Neither charge nor mass

 

Answer : A

 

Question: The number of valence electrons determines:

(a) Physical properties of elements

(b) Chemical properties of elements

(c) Both physical and chemical properties of elements

(d) Neither physical nor chemical properties of elements 

 

Answer : B

Question: Which of the following correctly represents the electronic distribution in the Mg atom?
(a) 3, 8, 1
(b) 2, 8, 2
(c) 1, 8, 3
(d) 8, 2, 2

Answer : B

Question: The electron should be filled in the orbital in accordance with the increasing order of their energy. This statement is related with
(a) Affbau principle
(b) Pauli principle
(c) Hund's principle
(d) Plank's rules

Answer : A

Question: The ion of an element has 3 positive charges. Mass number of the atom 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

Answer :  B

Question: An neutral element A has 3 electrons, the atomic number of an element is _______.
(a) 1
(b) 2
(c) 5
(d) 3

Answer :  C

Question: The isotope deuterium of hydrogen has
(a) No neutrons and one proton
(b) One neutrons and two protons
(c) One electron and two neutron
(d) One proton and one neutron

Answer :  D

Question: What prevents an atom from being collapsed?
(a) The nuclear forces
(b) Movement of electrons in discrete energy levels
(c) The electron-electron repulsions
(d) All of these

Answer.   B

Question: Which of the following statements about Rutherford’s model of atom are correct?
(i) Considered the nucleus as positively charge(d)
(ii) Established that the a-particles are four times as heavy as a hydrogen atom.
(iii) Can be compared to solar system.
(iv) Was in agreement with Thomson’s model.
(a) (i) and (iii)
(b) (ii) and (iii)
(c) (i) and (iv)
(d) only (i)

Answer :   A

Question: What is an electron?
(a) A wave
(b) A particle
(c) Either of two, depending on how it is observed
(d) Neither of these

Answer :   C

Question: The nucleus of an atom contains:
(a) Protons
(b) Electrons
(c) Protons and neutrons
(d) Neutrons

Answer :   C

Question: Which scientist gave the concept of fixed energy levels around the nucleus?
(a) Ernest Rutherford
(b) Neils Bohar
(c) J.J.Thomsan
(d) None of these

Answer :  B

Question: In an atom, the constituent electrons:
(a) Do not move
(b) Are uniformly distributed
(c) Move around the nucleus in fixed energy levels.
(d) Move around the nucleus in a random way.

Answer :  C

Question: Which of the following pairs are isotopes?
(a) Oxygen and ozone
(b) Ice and steam
(c) Nitric oxide and nitrogen dioxide
(d) Hydrogen and deuterium

Answer : D

Question:Which of the following has a charge of +1 and a mass of 1 amu?
(a) A neutron
(b) A proton
(c) An electron
(d) A helium nucleus

Answer : B

Question: Members of which of the following have similar chemical properties?
(a) Isotope
(b) Isobars
(c) Allotropes
(d) Both isotopes and allotropes

Answer :  C

Question: J. J. Thomson was awarded the Nobel Prize for Physics for his work on the discovery of electrons. Which of the following was/were suggested by Thomson in his model of atom?
(a) An atom consists of a positively charged sphere and the electrons are embedded in it.
(b) An atom consists of a negatively charged sphere and the electrons are embedded in it.
(c) The negative and positive charges are equal in magnitude.
(d) Both (1) and (3)

Answer :  D