Book of 9th (ICSE board) ch -4 Atomic structure and chemical bonding .
1. What is the contribution of the following in Atomic 13. Name the sub-atomic particle whose charge is:
(a) structure. +1 b) -1 (c) 0.
(a) Maharshi Kanada (b) Democritus ? 14. (a) Which metal did Rutherford select for his a particle
scattering experiment and why ? State Dalton's atomic theory.
3. What is an a (alpha) particle ?
4, What are cathode rays? How are these rays formed?
5. What is the nature of charge on (1) cathode rays (i) anode
(b) What do you think would be the observation of
-particle scattering experiment if carried out on
(i) heavy nucleus like platinum (ii) light nuclei
like lithium.
rays? 15. On the basis of Rutherford's model of an atom, which
6. How are X-rays produced1?
7. Why were anode rays also called as 'canal rays' ?
8. How do cathode rays differ from anode rays
subatomic particle is present in the nucleus of an atom ?
16. Which part of atom was discovered by Rutherford.
17. How was it shown that atom has empty space ?
18. State one major drawback of Rutherford's model.
19. In the figure given alongside
9. State one observation which shows that atom is not
indivisible.
10. (a) Name an element which does not contain neutron.
b) If an atom contains one electron and one proton, will
it carry any charge or not ?
(a) Name the shells denoted
by A, B and C. Which
shell has least energy ?
11. On the basis of Thomson's model of an atom, explain how b) Name X and state the
an atom as a whole is neutral. charge on it.
12. Which sub-atomic particle was discovered by (c) The above sketch is of .... model of an atom.
(a) Thomson (b) Goldstein (c) Chadwick. 20. Give the postulates of Bohr's atomic model.
Answers
Answer:
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Explanation:
2. State Dalton's atomic theory.
Solution:
Dalton atomic theory states that atoms are indivisible particles which are the fundamental building blocks of
matter. He states that the existence of different types of matter are due to different types of atoms.
Main postulates of Dalton's atomic theory:
Matter consists of very small and indivisible particles called atoms.
Atoms can neither be created nor be destroyed.
The atoms of an element are alike in all respects, but they differ from the atoms of other
elements.
Atoms of an element combine in small numbers to form molecules.
Atoms of one element combine with atoms of another element in a simple ratio to form
molecules of compounds.
Atoms are the smallest units of matter which can take part in a chemical reaction.