STRUCTURE OF THE ATOM 

Chapter-4

1. Compare the properties of electrons, protons and neutrons.

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

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3. What are the limitations of Rutherford's model of the atom?

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4. Describe Bohr's model of the atom.

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

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6. Summarise the rules for Writing of distribution of electrons in various shells for the first eighteen elements.

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7. Define valency by taking examples of silicon and oxygen.

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

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

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10. If bromine atom is available in the form of, say, two isotopes

79 Br (49.7%) and 81 Br (50.3%), calculate the average atomic mass 

35                                        35

of bromine atom.

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11. The average atomic mass of a sample of an element X is 16.2 u. What are the percentages of isotopes 16 X and 18 X in the sample?

   Ans:                                                          8                   8

12. If Z=3, what would be the valency of the element? Also, name the element. 

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13. Composition of the nuclei of two atomic species X and Y are given as under

                                         X        Y

protons               =          6         6

 Neutrons           =          6         8

Give the mass numbers of X and Y. what is the relation between the two species?

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14. For the following statements, write T for True and F for False.

(a)  J.J Thomson proposed that the nucleus of an  atom contains only nucleons.

(b) A neutron is formed by an electron and a proton combining together. There, it is neutral.

                                                                          times that of proton. 
(c) The mass of an electron is about 

 


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15. Rutherford' s alpha-particle scattering experiment was responsible for the discovery of

(a) Atomic Nucleus               (b) Electron

(c) proton                                (d) Neutron

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16. isotopes of an element have

(a) the same physical properties

(b) different chemical properties

(c) different number of neutrons

(d) different atomic numbers.

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17. Number of valence electrons in C1- ion are:

(a) 16      (b) 8       (c)  17      (d)  18

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18.  Which one of the following is a correct electronic configuration of sodium?

(a) 2,8      (b)  8,2,1   (c)  2,1,8     (d) 2,8,1.

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19.  Complete the following table.






type: Kalpana Hazarika

Post ID: DABP001772