Worksheet: Structure of the Atom - Science Class 9

Multiple Choice Questions

Q1: The nucleus of an atom consists of ______. 
(a) Protons
(b) Electrons and neutrons
(c) Protons and neutrons
(d) Neutrons

Q2: What is the maximum number of electrons which can be present in K and L shells in an atom?
(a) 2 and 8
(b) 2 and 18
(c) 2 and 32
(d) 8 and 18

Q3: Rutherford's alpha-particle scattering experiment was responsible for the discovery of
(a) Atomic Nucleus
(b) Electron
(c) Proton
(d) Neutron

Q4: Isotopes of element have:
(a) The same physical properties
(b) Different chemical properties
(c) Different number of neutrons
(d) Different atomic numbers

Q5: Number of valence electrons in Cl^– ion are:
(a) 16
(b) 8
(c) 17
(d) 18

Q6: An element has electronic configuration 2,8,4 it will be classified as
(a) Metal
(b) Non metal
(c) Metalloid
(d) None of these

Q7: 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

Q8: The nucleus of the hydrogen atom is called as
(a) Neutron
(b) Electron
(c) Proton
(d) Nucleons

Q9: 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

Q10: 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

Fill in the Blank

Q1: According to Maharishi Kanad, the tiniest to tiny particle of a pure substance is called _________.
Q2: An atom is the smallest unit of an element which takes part in a _________.
Q3: Mass of an electron is 1/1837 times less than the mass of one atom of__________.
Q4: The K-shell of any atom cannot have more than _________ electrons.
Q5: Isotopes are the atoms of ___________ element, having same atomic number but different mass number.

True or False

Q1: Radioactive isotope of iodine is used for making the medicine called tincture iodne.
Q2: J.J. Thomson proposed that the nucleus of an atom contains only nucleons.
Q3: The K-shell of any atom cannot have more than _________ electrons.
Q4: The innermost atomic shell can hold a maximum of 18 electons.
Q5: Nuclear chemistry has nothing to do with the electrons present in an atom.

Very Short Answer Questions

Q1: Out of proton and neutron, which is heavier?
Q2: Were neutrons known at the time Rutherford performed the scattering experiment?
Q3: Why is proton so named?
Q4: What is the number of electrons in the valence shell of chlorine (Z = 17)?
Q5: What is the basic difference between the isotopes of an element?

Short Answer Questions