Assertion and Reason Questions for Class 9 Science Chapter 4 Structure of Atom
Q.1. Assertion : For noble gases, valency is zero.
Reason : Noble gases have 8 valence electrons.
Q.2. Assertion : Thomson’s atomic model is known as ‘raisin pudding’ model.
Reason : The atom is visualized as a pudding of positive charge with electrons (raisins) embedded in it.
Q.3. Assertion : The mass of the total number of protons and neutrons is a measure of the approximate mass of an atom.
Reason : The mass of an electron is negligible.
Q.4. Assertion : Electrons moving in the same orbit will lose or gain energy.
Reason : On jumping from higher to lower energy level, the electron will gain energy
Q.5. Assertion : Isotopes are electrically neutral.
Reason : Isotopes are species with same mass number but different atomic numbers
Q.6. Assertion : Atom is electrically neutral.
Reason : A neutral particle, neutron is present in the nucleus of atom.
Q.7. Assertion : The size of the nucleus is very small as compared to the size of the atom.
Reason : The electrons revolve around the nucleus of the atom
Q.8. Assertion : Isotopes are electrically neutral.
Reason : Isotopes of an element have equal number of protons and electrons.
Q.9. Assertion : Isobars are identical in chemical properties.
Reason : Isobars have same atomic number.
Q.10. Assertion : Anions are larger in size than the parent atom.
Reason : In an anion, the number of protons in the nucleus is less than the number of electrons moving around it