class 9 chemistry chapter 4 practice sheet --- the structure of atom
CLASS: IX; CHEMISTRY
CHAPTER-4
THE STRUCTURE OF ATOM (HLP)
1.Will 35CIand 37CI
have different valencies? Justify your answer.
Solution:
2.Find out the valency of the atoms represented by the Fig. 4.3 (a) and (b).
3.One electron is present in the outer most shell of the atom of an element X.
What would be the nature and value of charge on the ion formed if this electron
is removed from the outer most shell?
4.In the atom of an element X, 6 electrons are present in the outermost shell.
If it acquires noble gas configuration by accepting requisite number of
electrons, then what would be the charge on the ion so formed?
5.What information do you get from the Fig. 4.4 about the atomic number, mass
number and valency of atoms X, Y and Z? Give your answer in a tabular form.
6.In response to a question, a
student stated that in an atom, the number of protons is greater than the
number of neutrons, which in turn is greater than the number of electrons. Do
you agree with the statement? Justify your answer.
7.Calculate the number of neutrons
present in the nucleus of an element X which is represented 3115X
Match the names of the Scientists given in column A with their contributions
towards the understanding of the atomic structure as given in column B
|
Column (A) |
Column (B) |
||
|
(a) |
Ernest Rutherford |
(i) |
Indivisibility of
atoms |
|
(b) |
JJ.Thomson |
(ii) |
Stationary orbits |
|
(c) |
Dalton |
(Hi) |
Concept of
nucleus |
|
(d) |
Neils Bohr |
(iv) |
Discovery of
electrons |
|
(e) |
James Chadwick |
(v) |
Atomic number |
|
(f) |
E. Goldstein |
(vii) |
Neutron |
|
(9) |
Mosley |
(vii) |
Canal rays |
8.The atomic number of calcium and argon are 20 and 18 respectively, but the
mass number of both these elements is 40. What is the name given to such a pair
of elements?
Complete the Table 4.1 on the basis of information available in the symbols
given below.
(a) 3517Cl
(b) 126C
(C)8135Br
|
Element |
np |
nn |
9.Helium atom has 2 electrons in its
valence shell but its valency is not 2, Explain.
10.In the Gold foil experiment of
Geiger and Marsden, that paved the way for Rutherford’s model of an atom, ~
1.00% of the α-particles were found to deflect at angles > 50°. If one mole
of a-particles were bombarded on the gold foil, compute the number of
a-particles that would deflect at angles less than 50°.
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