MCQ Questions for Class 9 Chemistry Structure Of The Atom Quiz 15

The number that represents, how many times one atom of an element is heavier than mass of one atom of carbon

$^{12}_6C$ is called :

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Atomic number
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Atomic weight
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Relative atomic mass
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All of these

The fundamental particles present in the nucleus of an atom are:

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Alpha particle and electrons
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Neutrons and protons
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Neutrons and electrons
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Electrons, neutrons and protons

The

$\alpha -particle$ scattering experiment of Rutherford concluded that

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The nucleus is made up of protons and neutrons
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The number of electrons is exactly equal to number of protons in atom
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The positive charge of the atom is concentrated in a very small space
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Electrons occupy discrete energy levels

Which is correct statement about proton?

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Proton is nucleus of deuterium.
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Proton is ionized oxygen molecule.
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Proton is ionized hydrogen atom.
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None of these

Explanation

When a hydrogen atom loses an electron, it becomes an ion having only one proton and no electrons. So, we can say that a proton is an ionised hydrogen atom.

$H \xrightarrow{Loses\ electron} H^+ (proton)$

The size of nucleus is of the order of :

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${10^{ - 12}}\;{\text{m}}$
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${10^{ - 8}}\;{\text{m}}$
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${10^{ - 15}}\;{\text{m}}$
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${10^{ - 10}}\;{\text{m}}$

Explanation

Size of the nucleus is very small and of order around

$10^{-15}m$ .

The time period of revolving in the third orbit of

$Li^{2+}$ ion is

$x$ second. The time period of revolution in the second orbit of

$He^+$ ion should be

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$x\ s$
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$\dfrac {3}{2}x\ s$
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$\dfrac {2}{3}x\ s$
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$\dfrac {8}{27}x\ s$

Which of following is not a conclusion of Rutherford's atomic model?

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Most of the part inside an atom is empty.
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Almost all mass of an atom is concentrated in the nucleus.
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The size of nucleus is very small in comparison to the size fo atom.
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Electron revolves round the nucleus in definite orbits.

In the Bohr's model of the hydrogen atom, let r, v and E represent the orbit radius, speed of the electron, respectively. Which of the following relation is proportional to the orbit number

$n$ ?

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$v\cdot r$
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$r/E$
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$r/V$
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$r\cdot E$

Which of the following contains same number of carbon atoms are in 6g of carbon?

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8g ethane
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8g methane
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21g propane
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28g CO

Which of the following is discrete in Bohr's theory ?

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Potential energy
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Kinetic energy
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Velocity
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Angular momentum

Explanation

Bohr's hypothesis:
1) Electrons revolves round the nucleus in water orbits.
2) Orbit of the electron around the nucleus can take only some special values of radius.
3) The energy of the atom as a definite value in these orbits.

4) In this Orbits, Angular momentum (e) of the electron is integral multiple of the plank's constant h divided by 2n i.e.

$l=n \dfrac{h}{2\pi}$ .

Hence option D is correct

CBSE Questions for Class 9 Chemistry Structure Of The Atom Quiz 15 - MCQExams.com

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Practice Class 9 Chemistry Quiz Questions and Answers

CBSE Questions for Class 9 Chemistry Structure Of The Atom Quiz 15 - MCQExams.com

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Practice Class 9 Chemistry Quiz Questions and Answers

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