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 of nucleus (d) Niels Bohr (iv) Discovery of electrons (e) James Chadwick (v) Atomic number (f) E. Goldstein (vi) Neutron (g) Moseley (vii) Canal rays

(a) Ernest Rutherford's gold foil experiment lead to the discovery of nucleus. (b) J.J. Thomson's cathode ray tube experiment showed that all atoms contain negatively charged subatomic particles, called electrons. (c) According to Dalton's atomic theory, all matter consists of indivisible particles called atoms. (d) According to Bohr's atomic theory, electrons orbit the nucleus at fixed energy levels called stationary orbits. (e) In the year 1932 James Chadwick discovered the subatomic particle neutron which is a neutral particle. (f) E.Goldstein discovered canal rays or anode rays. They are also called as positive rays. (g) Mosley gave the modern periodic law which states that, the physical and chemical properties of the elements are a periodic function of their atomic number. Column A Column B (a) Ernest Rutherford (iii) Concept of nucleus (b) JJ. Thomson (iv) Discovery of electrons (c) Dalton (i) Indivisibility of atoms (d) Niels Bohr (ii) Stationary orbits (e) James Chadwick (vi) Neutron (f) E.Goldstein (vii) Canal rays (g) Moseley (v) Atomic number

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Write down the electron distribution of chlorine atom. How many electrons are there in the $L$ shell? (Atomic number of chlorine is $17$ ).

Important Questions on Structure Of The Atom

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NCERT Exemplar Science - Class 9>Chapter 4 - Structure Of The Atom>Short Answer Questions>Q 26

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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NCERT Exemplar Science - Class 9>Chapter 4 - Structure Of The Atom>Short Answer Questions>Q 27

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.

Question Image

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NCERT Exemplar Science - Class 9>Chapter 4 - Structure Of The Atom>Short Answer Questions>Q 28

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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NCERT Exemplar Science - Class 9>Chapter 4 - Structure Of The Atom>Short Answer Questions>Q 29

Calculate the number of neutrons present in the nucleus of an element X which is represented

{}_{15}^{31}X

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IMPORTANT

NCERT Exemplar Science - Class 9>Chapter 4 - Structure Of The Atom>Short Answer Questions>Q 30

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 of nucleus
(d) Niels Bohr	(iv) Discovery of electrons
(e) James Chadwick	(v) Atomic number
(f) E. Goldstein	(vi) Neutron
(g) Moseley	(vii) Canal rays

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NCERT Exemplar Science - Class 9>Chapter 4 - Structure Of The Atom>Short Answer Questions>Q 31

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?

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NCERT Exemplar Science - Class 9>Chapter 4 - Structure Of The Atom>Short Answer Questions>Q 32

Complete the Table 4.1 on the basis of information available in the symbols given below.

(a) ${}_{17}^{35}{Cl}$

(b) ${}_{6}^{12}C$

Element	$n_{p}$	$n_{n}$

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9th CBSE

IMPORTANT

NCERT Exemplar Science - Class 9>Chapter 4 - Structure Of The Atom>Short Answer Questions>Q 32

Complete the Table 4.1 on the basis of information available in the symbols given below.

{}_{6}^{12}C

Element

n_{p}

n_{n}

Write down the electron distribution of chlorine atom. How many electrons are there in the L shell? (Atomic number of chlorine is 17).

Important Questions on Structure Of The Atom

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Write down the electron distribution of chlorine atom. How many electrons are there in the $L$ shell? (Atomic number of chlorine is $17$ ).