Structure of the Atom (Practice Sheet, Class 9)

(1)Write electronic configuration of element X which has atomic number = 15.Write its valency also.

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Structure of the atom, Q 2, practice sheet, NCERT, class 9Solution –

(3) Differentiate between atomic number and mass number.

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(4) An element has mass number equal to 32. What do you understand by it?

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(5)If number of electron in outermost shell of an atom is 6. What will be the charge of atom?

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(6) Complete the table given below –

SN Atomic number Number of proton Number of neutron Mass number Distribution of electrons Valency
1. 18   2 20 2,8,8
2. 4 5
3. 14 5 2,8,4

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Structure of the atom, Q 7, practice sheet, NCERT, class 9Solution –

(8) Differentiate between average atomic mass and mass number.

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Structure of the atom, Q 9, practice sheet, NCERT, class 9

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(10) Who proposed that electrons are embedded in positive sphere-

(i) J.J.Thomson        (ii) Rutherford’s Model        (iii) Bohr’s Model

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Helping Topics

Structure of the atom

NCERT solutions, class 9

Atoms and Molecules

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