TextBook Solutions for Board of High School and Intermediate Education Uttar Pradesh Class 9 Science Chapter 5 The Fundamental Unit Of Life

Compare the properties of electron, proton and neutron.

What are the limitations of J.J. Thomson’s model of atom?

What are the limitations of Rutherford model of the atom?

Describe Bohr's model of the atom ?

Compare all the proposed models of an atom given in this chapter.

Summarize the rules for writing of distribution of electrons in various shells for the first eighteen elements.

Define valency by taking examples of silicon and oxygen.

Explain with examples, (i) Atomic number, (ii) Mass number, (iii) Isotopes, and (iv) Isobars. Give any two uses of isotopes also.

Na⁺ has completely filled K and L-shells. Explain.

If bromine atom is available in the form of, say, two isotopes ${}_{35}{}^{79}\mathrm{Br}$ (49.7%) and ${}_{35}{}^{81}\mathrm{Br}$ (50.3%), calculate the average atomic mass of bromine atom.