Atoms and Molecules Class 9 MCQ. We covered all the Atoms and Molecules Class 9 MCQ in this post for free so that you can practice well for the exam.
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Atoms and Molecules Class 9 Objective MCQ for Students
Which of the following is/are correct for the law of constant proportion? 1. It was given and stated by Lavoisier. 2. In a chemical substance, the elements are always present in definite proportions by mass.
(a) Only 1
(b) Only 2
(c) Both 1 and 2
(d) Neither 1 nor 2
Option b – Only 2
Which of the following is/are true for Dalton’s atomic theory? 1. All matter is made of tiny up very particles called atoms. 2. Atoms do not participate in chemical reactions. 3. Atoms are indivisible particles.
(a) 1 and 2
(b) 2 and 3
(c) 1 and 3
(d) 1, 2, and 3
Option c – 1 and 3
Which of the following is/are correct for molecules? 1. It is a group of two or more atoms that are chemically bonded together. 2. Atoms of only the same element join to form molecules. ( Atoms and Molecules Class 9 Objective )
(a) Only 1
(b) Only 2
(c) Both 1 and 2
(d) Neither 1 nor 2
Option a – Only 1
Which of the following are correctly matched? 1. Argon – monoatomic 2. Phosphorus – polyatomic 3. Chlorine – diatomic
(a) 1 and 2
(b) 2 and 3
(c) 1 and 3
(d) 1, 2, and 3
Option c – 1 and 3
Which of the following is/are correct for ions? 1. The charged species are known as ions. 2. A negatively charged ion is called a cation. 3. A group of atoms carrying a charge is known as a polyatomic ion.
(a) 1 and 2
(b) 2 and 3
(c) 1 and 3
(d) 1, 2, and 3
Option c – 1 and 3
Which of the following is/are correct for atomic mass? 1. It was proposed by Bohr. 2. It was explained by the law of constant proportions. ( Atoms and Molecules Class 9 Objective )
(a) Only 1
(b) Only 2
(c) Both 1 and 2
(d) Neither 1 nor 2
Option b – Only 2
………. represents the atoms and ………. represents molecular and compounds.
1) Names of formula
2) symbols & formula
3) formula & symbols
4) Names & valency
Option 2 – symbols & formula
What is the symbol of sodium ( Atoms and Molecules Class 9 Objective )
1) S
2) Na
3) K
4) Sd
Option 2 – Na
Latin word for water is
1) Hydro
2) Helios
3) Hydrogen
4) Oxy
Option 1 – Hydro
The gas which was first discovered in the sun
1) Hydrogen
2) Oxygen
3) Helium
4) Nitrogen
Option 3 – Helium
Law of definite proportion was given by ( Atoms and Molecules Class 9 Objective )
1) John Dalton
2) Lavoisier
3) Joseph Proust
4) Ritcher
Option 3 – Joseph Proust
Among the following the elements that are discovered and named after scientist
1) Einsteinium
2) Fermium
3) Rutherfordium and Mendelevium
4) all the above
Option 3 – Rutherfordium and Mendelevium
Law of conservation of mass was proposed by
1) Landolt
2) Lavoisier
3) Dalton
4) Proust
Option 2 – Lavoisier
Law of conservation of mass was experimentally verified by ( Atoms and Molecules Class 9 Objective )
1) Lavoisier
2) Landolt
3) Proust
4) Berzelius
Option 2 – Landolt
” A given chemical substance always contains the same elements combined in a fixed proportions by weight ” is called
1) Law of conservation of mass
2) Law of constant proportions
3) Law of definite proportions
4) both b & c
Option 2 – Law of constant proportions
Which postulate of Dalton’s theory is the result of law conservation of mass ( Atoms and Molecules Class 9 Objective )
1) matter can be neither created nor destroyed
2) atoms of different elements or different in properties
3) atoms similar elements or similar in properties
4) atoms is a smallest particle take part in chemical reactions
Option 1 – matter can be neither created nor destroyed
An element X forms the oxides containing 57.7% and 42.3% of Oxygen respectively. This indicates the law of
1) Definite proportions
2) Multiple proportions
3) Reciprocal proportions
4) None of these
Option 2 – Multiple proportions
A …….. is the smallest particle of an element or a compound that is capable of independent existence and retain all the properties of that substance. ( Atoms and Molecules Class 9 Objective )
1) Molecule
2) Compound
3) Atom
4) Mixture
Option 1 – Molecule
Mass of one mole of a substance is called
1) Atomic mass
3) Molar mass
4) Unit mass
Option 3 – Molar mass
The total mass of the products formed in a chemical reaction is exactly equal to the mass of the reactants. This is known as
1) Law of conservation of mass
2) Law of multiple proportions
3) Law of definite proportions
4) None of these
Option 1 – Law of conservation of mass
In a chemical substance the elements are always present in fixed proportions by mass. This is known as the : ( Atoms and Molecules Class 9 Objective )
1) Law of conservation of mass.
2) Law of multiple proportions
3) Law of definite proportions
4) None of these
Option 3 – Law of definite proportions
An ………. is the smallest particle of an element that can participate in chemical reaction and retain all its properties.
1. Molecule
2) Compound
3) Atom
4) Mixture
Option 3 – Atom
The number of atoms constituting a molecule is known as its ( Atoms and Molecules Class 9 Objective )
1) Valency
2) Combining power
3) Atomicity
4) none
Option 3 – Atomicity
Which of the following is mono atomic
1) Hydrogen
2) Ozone
3) Nitrogen
4) Helium
Option 4 – Helium
The symbol for the element chromium is
1) Cr
2) Cl
3) C
4) Ca
Option 1 – Cr
Greek name for sun is ( Atoms and Molecules Class 9 Objective )
1) Hydro
2) Oxy
3) Helio
4) Helios
Option 3 – Helio
Which of the following does not change when a chemical reaction takes place
1) Volume
2) Mass
3) physical properties
4) chemical properties
Option 2 – Mass
Molecules of the following element are made up of only one atom of that element ( Atoms and Molecules Class 9 Objective )
1) Iron
2) Sodium
3) Helium
4) Chlorine
Option 3 – Helium
Argon is
1) monoatomic
2) diatomic
3) triatomic
4) polyatomic
Option 1 – monoatomic
Which of the following is not the postulate of Dalton’s atomic theory of matter ( Atoms and Molecules Class 9 Objective )
1) Each element is made up of extremely small particles called atoms
2) Atoms of a given element are identical in chemical properties but may have be different physical properties
3) Atoms cannot be created or destroyed
4) Compounds are formed by the chemical union of atoms of two or more elements in a fixed proportion which are simple whole number
Option 2 – Atoms of a given element are identical in chemical properties but may have be different physical properties
Matter consists of indivisible particles called
1) Molecules
2) Compounds
3) Elements
4) Atoms
Option 4 – Atoms
When the particles of a substance contain only one type of atoms, the substance is called
1) Element
2) Compound
3) Molecule
4) None
Option 1 – Element
Choose the odd molecule
1) Argon molecule
2) Chlorine molecule
3) Oxygen molecule
4) Fluorine molecule
Option 1 – Argon molecule
Bohr,s theory is valid for
1) All atoms
2) All ions
3) Any atom or ion having single electron
4) All molecules
Option 3 – Any atom or ion having single electron
The sub-shells present in L- shell are
1) s and d
2) s and p
3) s,p and d
4) s,p,d and f
Option 2 – s and p
Rutherford suggested that atoms are
1) spherical
2) cylindrical
3) tetrahedral
4) pyramidal
Option 1 – spherical
Bohr’s model could not account for
1) Seebeck effect
2) Raman’s effect
3) Condensation effect
4) Zeeman effect
Option 4 – Zeeman effect
The region in space where there is a finite probability of finding electron is
1) Atomic number
2) Atomic orbital
3) Atomic particle
4) Ground state
Option 2 – Atomic orbital
Gold foil was used in Rutherford’s scattering experiment because it
1) has high refractive index
2) has high density
3) is highly malleable
4) is high ductile
Option 3 – is highly malleable
According to Bohr Burry the maximum number of electrons that can be accommodated in each atomic orbital is
1) 8
2) 2
3) 10
4) 6
Option 2 – 2
Atomic number of A is 10 and element B is 11. Which statement about A and B is correct
1) Both are chemically inert
2) B is chemically inert
3) B is more reactive than A
4) A is more reactive than B
Option 3 – B is more reactive than A
Isotopes are
1) atoms of same element
2) atoms of different elements
3) molecules of same element
4) radicals of the same element
Option 1 – atoms of same element
Isobars have
1) same no. of protons and different electron
2) different number of protons and neutrons
3) same no. of electrons and neutrons
4) same no. of neutrons
Option 2 – different number of protons and neutrons
The orbits of an atom are also called energy levels because these are spheres containing definite energy.
1) assertion is correct and reason is correct
2) assertion is correct but reason is wrong
3) assertion is wrong but reason is correct
4) assertion is wrong and reason is wrong
Option 2 – assertion is correct but reason is wrong
The size of an atom is decided by
1) mass of the atom
2) no. of protons
3) no. of protons and neutrons
4) no. of electrons
Option 4 – no. of electrons
Calcium has 20 electrons. These occupy K,L,M, and N shells. Which shell or shells are incomplete
1) L,M,N shells
2) M,N shells
3) N shells
4) K,L,M,N shells
Option 2 – M,N shells
There is no difference between valency and valence electrons except in case of
1) elements of group 2
2) elements of group 3
3) elements of group 4
4) elements of group 5
Option 4 – elements of group 5
Which of the following statements is wrong for the model of an atom as proposed by Rutherford
1) The atom consists of a positively charged centre called nucleus
2) Nucleus consists of protons and neutrons
3) Most of the mass is concentrated in the nucleus
4) The volume of nucleus is very small as compared to the total volume of the atom
Option 2 – Nucleus consists of protons and neutrons
Rutherford alpha- particle scattering experiment was responsible for the discovery of
1) Nucleus
2) neutron
3) mass number
4) atomic number
Option 1 – Nucleus
Mass number of an element can be obtained by adding
1) Number of electrons and neutrons
2) number of protons and neutrons
3) number if electrons and protons
4) number of electrons, protons and neutrons
Option 2 – number of protons and neutrons
If a neutral atom has three shells completely filled up, then the number electrons of the atom is
1) 28
2) 32
3) 30
4) 18
Option 3 – 30
Which one is not true for two isotopes?
1) Similar mass number
2) Similar atomic number
3) Similar chemical properties
4) Similar electronic configurations
Option 1 – Similar mass number
Calcium, Magnesium, Sulphur and Chlorine have atomic numbers 20, 12, 16, 17 respectively. Which of these does not show a valency of 2?
1) Calcium
2) Magnesium
3) Sulphur
4) Chlorine
Option 4 – Chlorine
The number of isotopes that are exhisted for both xenon and cesium are
1) 46
2) 16
3) 26
4) 36
Option 4 – 36
The isotope of iodine is used in the treatment of
1) cancer
2) goitre
3) age of fossil
4) fuel in nuclear react
Option 2 – goitre
Among the following which elements can show multiple valencies
1) sulphur
2) phosphorus
3) sodium
4) both a, b
Option 4 – both a, b
Isotopes have different physical properties due to
1) same number of protons
2) same number of electrons
3) same number of neutrons
4) Different number of neutrons or different mass numbers
Option 4 – Different number of neutrons or different mass numbers
An atom absorbs a UV photon of 200 nm and re-emits two photons. If the wavelength of one of the emitted photons is 700 nm. The wavelength of the second emitted photon will be ……….
(A) 900 nm
(B) 500 nm
(C) 280 nm
(D) 7000 nm
Option c – 280 nm
In hydrogen atoms, if the radius of an orbit is made four times that of a smaller orbit, then the angular momentum of an electron becomes ……….. the angular momentum of an electron in a smaller orbit.
(A) twice
(B) half
(C) four times
(D) thrice
Option a – twice
Which one of the following has the least energy?
(A) n = 3, 1 = 2
(B) n=2, l=1
(C) n = 3, l = 1
(D) n = 4, l=0
Option b – n=2, l=1
The mass of an electron is equal to the mass of a/an ……….
(A) alpha particle
(B) beta particle
(C) neutron
(D) gamma rays
Option b – beta particle
Select the number of electrons that have n = 2 and s = +1/2.
(A) 3
(B) 4
(C) 8
(D) 9
Option b – 4
The orbital angular momentum of an electron depends on ………..
(A) only l
(B) only n and l
(C) only n and m
(D) only m and l
Option a – only l
The spectral line corresponding to the transition of an electron in the H-atom from the 4th orbit to the 3rd orbit is known as ………. series.
(A) Balmer
(B) Brackett
(C) Paschen
(D) Pfund
Option c – Paschen
Violet light can eject electrons from the surface of potassium metal but red light cannot because ……….
(A) the intensity of violet light is greater than red light and is enough to eject electrons
(B) the wavelength of violet light is greater than red light and is enough to eject electrons
(C) the frequency of red light is lower than violet light and is not enough to eject electrons
(D) none of these
Option c – the frequency of red light is lower than violet light and is not enough to eject electrons
If the magnetic quantum number of an electron is represented by – 3, then which of the following can be its principal quantum number?
(A) 2
(B) 3
(C) 4
(D) 1
Option c – 4
An electron revolving around the nucleus behaves as a standing wave only when the circumference is equal to ………
(A) the radius of an orbit
(B) fractional multiple of the wavelength
(C) the velocity of an electron
(D) an integral multiple of the wavelength
Option d – an integral multiple of the wavelength
Which of the following is CORRECT for both cathode rays and anode rays?
(A) The particles of both rays travel in a straight line and in the same direction.
(B) In the presence of an electric field, both the rays deflect towards the negative electrode.
(C) Both rays are affected by a magnetic field.
(D) The particles of both rays are electrically neutral.
Option c – Both rays are affected by a magnetic field.
The orbitals described by the following quantum numbers are ……….. respectively. (1) n = 5,1 = 3 (II) n = 6,1=0
(A) (I) = 5f; (II) = 6s
(B) (1)=5s; (II) = 6f
(C) (I) = 5d; (II) = 6s
(D) (I) = 5f; (II) = 6p
Option a – (I) = 5f; (II) = 6s
For an electron in Bohr’s orbit, the energy difference between successive orbits in hydrogen atom when going away from the nucleus ………..
(A) increases
(B) remain unchanged
(C) decreases
(D) first decreases and then increases
Option c – decreases
When an electron jumps from n = 3 to n = 1 in Bohr’s atom, the possible number of spectral lines is/are ………
(A) 4
(B) 2
(C) 1
(D) 3
Option d – 3
The orbitals, 2px and 2py differ in their ……..
(A) orientation
(B) shape
(C) energy
(D) size
Option a – orientation
The ionization energy of a hydrogen atom is ……..
(A) 13.6 eV
(B) 4.08 eV
(C) 5.44 eV
(D) 2.72 eV
Option a – 13.6 eV
Bohr’s model can be applied to ……….
(A) elements containing more than one electron
(B) ions containing more than one electron
(C) atoms or ions containing one electron
(D) only hydrogen atom
Option c – atoms or ions containing one electron
The ratio of the energies of photons of 3000 Å to that of 9000 Å is ……….
(A) 3 : 1
(B) 9 : 1
(C) 1 : 3
(D) 1 : 9
Option a – 3 : 1
The number of radial nodes for 4d orbital is ……..
(A) 1
(B) 2
(C) 3
(D) 4
Option a – 1
The charge-to-mass ratio of cathode ray particles obtained by using helium gas is ………. that of obtained by using hydrogen gas.
(A) greater than
(B) smaller than
(C) half
(D) equal to
Option d – equal to
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