Available Answers

1. 1.

   Fill in the blank spaces by choosing the correct words from the given list :

   List : hydrogen, valence, positively, orbits, anu

   1. According to J.J. Thomson's model of atom, the electrons are embedded in a thinere spread ____________ charged sphere of protons.
   2. The fixed paths along which the electrons revolve, ground the nucleus are called ____________.
   3. The electrons in the outermost orbit of an atom are called ____________ electrons.
   4. According to Maharishi Kanad, the tiniest of the tiny particle of a pure substance is called ____________.
   5. The mass of an electron is 1/1837 times than mass of one atom of ____________.
2. 2.

   Statements given below are incorrect. Write the correct statements.

   1. Chadwick discovered the electron.
   2. A proton is 1837 times heavier than an electron.
   3. The electrons in the outermost orbit of an atom are called bound electrons.
   4. The mass of neutron is equal to the hydrogen atom and it is positively charged.
   5. The core of an atom is called its centre.
3. 3.

   Match the statements in Column A, with those in Column B.

   Column A	Column B
   1. A positively charged particle within the nucleus of an atom.	(a) Nucleons
   2. The name of electrons in the outermost orbit.	(b) Electron
   3. An assembly of protons and neutrons within the nucleus of an atom.	(c) Neutron
   4. An almost weightless particle in an atom which is negatively charged.	(d) Proton
   5. A particle almost as heavy as proton, having no electric charge.	(e) Valence electrons

    

4. 4.

   Write 'true' or 'false' in front of following statements :

   1. The core of an atom is called nucleus.
   2. Proton is a positively charged particle having a negligible mass.
   3. Paramanu is made up of two or more anus.
   4. The electron as an integral part of all kinds of atom of different elements was discovered by Rutherford.
   5. The electrons in the shell close to the nucleus are called bound electrons.
5. 5.

   Tick (√) the most appropriate answer.

   1. Which one of the following proposed atomic theory of matter?
      1. John Dalton
      2. J.J. Thomson
      3. Rutherford
      4. Niels Bohr
   2. Nucleons are
      1. protons only
      2. neutrons only
      3. protons and nuetrons
      4. protons and electrons
   3. The mass of an atom is due to the assembly of
      1. protons
      2. neutrons
      3. protons and electrons
      4. protons and neutrons
   4. The electrons in the outermost orbit of an atom are held very weakly by the nucleus and are called :
      1. lose electrons
      2. weak electrons
      3. valence electrons
      4. none of the above
   5. The alpha particles used by Rutherford for bombarding the gold foil :
      1. have a mass of 2 amu charge +4
      2. have a mass of 4 amu and charge +2
      3. have a mass of 4 amu and charge +4
      4. have a mass of 1 amu an id charge +1
6. 6.

   State five main assumptions of Dalton's atomic theory of matter.