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What are canal rays?
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If an atom contains one electron and one proton. Will it carry any charge or not?
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On the basis of Thomson's model of an atom, explain how the atom is neutral as a whole.
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On the basis of Rutherford's model of an atom, which sub-atomic particle is present in the nucleus of an atom?
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Draw a sketch of Bohr's model of an atom with three shells.
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What do you think would be the observation if the a-particle scattering experiment is carried out using a foil of a metal other than gold?
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Name the three sub-atomic particles of an atom.
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Helium atom has an atomic mass of 4 u and two protons in its nucleus. How many neutrons does it have?
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Write the distribution of electrons in carbon and sodium atoms.
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If K and L shells of an atom are full, then what would be the total number of electrons in the atom?
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How will you find the valency of chlorine, sulphur and magnesium?
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If number of electrons in an atom is 8 and number of protons is also 8, then
(i) what is the atomic number of the atom ? and
(ii) what is the charge on the atom?
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Atomic numbers of oxygen and sulphur are 8 and 16 respectively. Oxygen atom has 6 neutrons and sulphur atom has 16 neutrons. Find out the mass number of oxygen and sulphur atom.
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For the symbol H, D and T tabulate three sub-atomic particles found in each of them.
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Write the electronic configuration of any one pair of isotopes and isobars.
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Compare the properties of electrons, protons and neutrons.
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What are the limitations of J.J. Thomson's model of the atom?
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What are the limitations of Rutherford's model of the atom?
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Describe Bohr's model of the atom.
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Compare all the proposed models of an atom given in this chapter.
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Summarize the rules for writing the distribution of electrons in various shells for the first eighteen elements.
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Define valency by taking examples of silicon and oxygen.
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Explain with examples (i) Atomic number, (ii) Mass number, (iii) Isotopes and (iv) Isobars.
Give any two uses of isotopes.
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Na+ has completely filled K and L shells. Explain.
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If bromine atom is available in the form of, say two isotopes 
(49.70%) and 
(50.30%) calculate the average atomic mass of bromine atom.
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The average atomic mass of sample of an element X is 16.2 u. What are the percentages of isotopes
and
in the sample?
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If Z = 3, what would be the valency of the element? Also, name the element.
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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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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. Therefore, it is neutral.
(c) The mass of an electron is about 1/2000 times that of proton.
(d) An isotope of iodine is used for making tincture iodine, which is used as a medicine.
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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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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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Number of valence electrons in Cl- ion are :
(a) 16 (b) 8
(c) 17 (d) 18
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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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Complete the following table.
|
Atomic number
|
Mass number
|
Number of neutrons
|
Number of protons
|
Number of electrons
|
Name of the atomic species
|
|
9
|
-
|
10
|
-
|
-
|
-
|
|
16
|
32
|
-
|
-
|
-
|
Sulphur
|
|
-
|
23
|
-
|
12
|
-
|
-
|
|
-
|
2
|
-
|
1
|
-
|
-
|
|
-
|
1
|
0
|
1
|
0
|
-
|
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question_answer35)
Which of the following correctly represent the electronic distribution in
the Mg atom?
(a) 3, 8, 1 (b) 2, 8, 2
(c) 1, 8, 3 (d) 8, 2,
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question_answer36)
Rutherford's alpha(a)
particles scattering experiment resulted into discovery of
(a) electron (b) proton (c)
nucleus in the atom (d) atomic mass
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question_answer37)
The number of electrons in an element X is 15 and the
number of neutrons is 16. Which of the following is the correct representation
of the element?
(a)
(b)
(c)
(d)
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question_answer38)
Dalton's atomic theory successfully explained.
(i) law of conservation of mass (ii)
law of constant composition
(iii) law of radioactivity (iv)
law of multiple proportion
(a) (i), (ii) and (iii) (b) (i), (iii) and (iv) (c)
(ii), (iii) and (iv) (d) (i), (ii) and (iv)
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question_answer39)
Which of the following statements about Rutherford's model
of atom are correct?
(i) Considered the nucleus as positively charged.
(ii) Established that the cc-particles are four times as
heavy as a hydrogen atom.
(iii) Can be compared to solar system.
(iv) Was in agreement with Thomson's model.
(a) (i) and (iii) (b) (ii) and
(iii) (c) (i) and (iv) (d) Only (i)
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question_answer40)
Which of the following are true for an element?
Atomic number = number of protons + number of electrons
Mass number = number of protons + number of neutrons
Atomic number = number of protons = number of neutrons
Atomic number = number of protons = number of electrons
(a) (i) and (ii) (b) (i) and
(iii) (c) (ii) and (iii) (d) (ii) and
(iv)
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question_answer41)
In the Thomson's model of atom, which of the following
statements are correct?
(i) The mass of the atom is assumed to be uniformaly
distributed over the atom.
(ii) The positive charge is assumed to be uniformaly
distributed over the atom.
(iii) The electrons are uniformaly distributed in the
positively charged sphere.
(iv) The electrons attract each other to stabilize the
atom.
(a) (i), (ii) and (iii) (b) (i) and (iii) (c)
(i) and (iv) (d) (i), (iii) and (iv)
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question_answer42)
Rutherford's a-particle
scattering experiment showed that
(i) electrons have negative charge.
(ii) the mass and positive charge of the atom is
concentrated in the nucleus.
(iii) neutron exists in the nucleus.
(iv) most of the space in atom is empty.
Which of the above statements are correct?
(a) (i) and (iii) (b) (ii) and
(iv) (c) (i) and (iv) (d) (iii) and (iv)
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question_answer43)
The ion of an element has 3 positive charges. Mass number
of the atom is 27 and the number of neutrons is 14. What is the number of
electrons in the ion?
(a) 13 (b)
10 (c) 14 (d)
16
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question_answer44)
Identify the Mg2+ ion from the figure where, n
and p represent the number of neutrons and protons respectively.
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question_answer45)
(a) 
(b) 
(c) 
(d) 
In a sample of ethyl ethanoate 
the
two oxygen atoms have the same number of electrons but different, number of
neutrons, which of the following is the correct reason for it?
(a) One of the oxygen atoms have gained electrons
(b) One of the oxygen atoms has gained two neutrons
(c) The two oxygen atoms are isotopes
(d) The two oxygen atoms are isobars
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question_answer46)
Elements with valency 1 are
(a) always metals (b)
always metalloids
(c) either metals or non-metals (d)
always non-metals
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question_answer47)
The first model of an atom was given by
(a) N Bohr (b) E Goldstein (c)
Rutherford (d) JJ Thomson
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question_answer48)
An atom with 3 protons and 4 neutrons will have a valency
of
(a) 3 (b)
7 (c) 1 (d)
4
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question_answer49)
The electron distribution in an aluminium atom is
(a) 1, 8, 3 (b) 2, 8,
2 (c) 8, 2, 3 (d) 2,
3, 8
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question_answer50)
Which of the following in figure do not represent Bohr's
model of an atom correctly?
(a) (i) and (ii) (b) (ii) and
(iii) (c) (ii) and (iv) (d) (i) and (iv)
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question_answer51)
Which of the following statement is always correct?
(a) An atom has equal number of electrons and protons
(b) An atom has equal number of electrons and neutrons
(c) An atom has equal number of protons and neutrons
(d) An atom has equal number of electrons, protons and
neutrons
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question_answer52)
Atomic models have been improved over the years. Arrange
the following atomic models in the order of their chronological order.
(i) Rutherford's atomic model
(ii) Thomson's atomic model
(iii) Bohr's atomic model
(a) (i), (ii) and (iii) (b) (ii), (iii) and
(i) (c) (ii), (i) and (iii) (d) (iii), (ii) and (i)
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question_answer53)
Is it possible for the atom of an element to have one electron,
one proton and no neutron. If so, name the element.
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question_answer54)
Write any two observations which support the fact that
atoms are divisible.
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question_answer55)
Will 
and
have
different valencies? Justify your answer.
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question_answer56)
Why did Rutherford select a gold foil in his 
ray
scattering experiment?
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question_answer57)
Find out the valency of the atoms represented by the
Figure (a) and (b).
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question_answer58)
One electron is present in the outermost 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 outermost shell?
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question_answer59)
Write down the electron distribution of chlorine atom. How
many electrons are there in the L-shell? Atomic number of chlorine is = 17.
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question_answer60)
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?
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question_answer61)
What information do you get from the figure about the
atomic number, mass number and valency of atoms X, Y and Z? Give your answer in
a tabular form.
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question_answer62)
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.
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question_answer63)
Calculate the number of neutrons present in the nucleus of
an element X which is represented as
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question_answer64)
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
|
(iii) Concept or nucleus
|
|
(d)
|
Neils Bohr
|
(iv) Discovery of electrons
|
|
(e)
|
James Chadwick
|
(v) Atomic number
|
|
(f)
|
E Goldstein
|
(vi) Neutron
|
|
(g)
|
Mosely
|
(vii)Canal rays
|
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question_answer65)
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?
A pair of elements having same mass number but different
atomic number is called isobars.
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question_answer66)
Complete the table on the basis of information available
in the symbols given below.
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question_answer67)
Helium atom has 2 electrons in its valence shell but its
valency is not 2. Explain.
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question_answer68)
Fill in the blanks in the following statements.
(a) Rutherford's a-particle scattering experiment lead to
the discovery of the..........
(b) Isotopes have same ......... but different...........
(c) Neon and chlorine have atomic numbers 10 and 17
respectively. Their valencies will be ......... and ......... respectively,
(d) The electronic configuration of silicon is .........
and that of sulphur is
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question_answer69)
An element X has a mass number 4 and atomic number 2.
Write the valency of this element.
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question_answer70)
Why do helium, neon and argon have a zero valency?
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question_answer71)
The ratio of the radii of hydrogen atom and its nucleus is
.
Assuming the atom and the nucleus to be spherical.
(a) What will be the ratio of their sizes ?
(b) If atom is represented by planet earth 
estimate
the size of the nucleus.
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question_answer72)
Enlist the conclusions drawn by Rutherford from his ray
scattering experiment.
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question_answer73)
In what way is the Rutherford's atomic model different
from that of Thomson's atomic model?
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question_answer74)
What were the drawbacks of Rutherford's model of an atom?
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question_answer75)
What are the postulates of Bohr's model of an atom?
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question_answer76)
Show diagrammatically the electron distributions in a
sodium atom and a sodium ion and also give their atomic number.
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question_answer77)
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 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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