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Multiple choice chemistry the structure of the atom discovery of charged particles the plum pudding atom discovery of electrons and protons

Nuclides having the same atomic and mass numbers are known as :

  1. isotones

  2. isomers

  3. isobars

  4. isotopes
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Nuclides having the same atomic and mass numbers are known as Isomers.

An atom that has an unbalanced ratio of neutrons to protons in the nucleus seeks to become more stable. The unbalanced or unstable atom tries to become more stable by changing the number of neutrons and/or protons in the nucleus. This can happen in several ways:

  • converting neutrons to protons
  • converting protons to neutrons
  • ejecting an alpha particle (two neutrons and two protons) from the nucleus.

 Isotones :any of two or more species of atoms or nuclei that have the same number of neutrons.

Isobars are atoms of different chemical elements that have the same number of nucleons.

Isotopes are variants of a particular chemical element which differ in neutron number, and consequently in nucleon number.

Multiple choice chemistry the structure of the atom discovery of charged particles the plum pudding atom discovery of electrons and protons

An atom has two main regions. Which are those?

  1. Planetary electrons and energy levels

  2. Nucleus and kernel

  3. Principal energy levels and energy sublevels

  4. Nucleus and energy levels
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

An atom has two main regions, these include nucleus and energy levels.
Nucleus contains protons and neutrons. Electrons revolve in circular energy levels.

Multiple choice chemistry the structure of the atom discovery of charged particles the plum pudding atom discovery of electrons and protons

The nucleus of the atom consists of:

  1. protons and neutrons

  2. protons and electrons

  3. neutrons and electrons

  4. protons, neutrons and electrons
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The nucleus of the atom consists of protons and neutrons. Electrons are present in extra nuclear part.
Note: Protons, electrons and neutrons are subatomic particles.

Multiple choice chemistry the structure of the atom discovery of charged particles the plum pudding atom discovery of electrons and protons

Radius of a nucleus is proportional to:

  1. $A$
  2. ${A}^{{1}/{3}}$
  3. ${A}^{2}$
  4. ${A}^{{2}/{3}}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Radius of a nucleus is proportional to $\displaystyle {A}^{{1}/{3}}$
$\displaystyle r=(1.4 \times 10^{-15}) \times {A}^{{1}/{3}}$
Where r is the radius of the nucleus with mass number A.
Here, the unit of radius is meters.  

Multiple choice chemistry the structure of the atom discovery of charged particles the plum pudding atom discovery of electrons and protons

The ratio of the volume of the atom and the volume of the nucleus is:

  1. ${10}^{10}$
  2. ${10}^{12}$
  3. ${10}^{15}$
  4. ${10}^{20}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The ratio of the volume of the atom and the volume of the nucleus is $\displaystyle 10^{15}$

The radius of an atomic nucleus is of the order of $\displaystyle {10}^{-13} cm$ or $\displaystyle {10}^{-15} m$ or one Fermi unit.

On the other hand, the radius of an atom is of the order of $\displaystyle {10}^{-8} cm$ or $\displaystyle {10}^{-10} m$ or one angstrom unit.

Note:
The radius of nucleus is much smaller than atomic radius.

The ratio of atomic radius to radius of nucleus is $\displaystyle \dfrac {{10}^{-10} m}{{10}^{-15} m}=10^5$

Volume is proportional to cube of radius.

The ratio of atomic radius to radius of nucleus is $\displaystyle  (10^5)^3 = 10^{15}$

Multiple choice chemistry the structure of the atom discovery of charged particles the plum pudding atom discovery of electrons and protons

Which is characteristic of unstable nucleus?

  1. $n/p$ ratio is high

  2. Low binding energy

  3. High packing fraction

  4. None of these
Reveal answer Fill a bubble to check yourself
A,B,C Correct answer
Explanation

It is the balance of protons and neutrons in a nucleus which determines whether a nucleus will be stable or unstable. Other factors that influence the stability of nucleus are binding energy and high packing fraction. 

So, the characteristics of unstable nucleus are
  1. $\dfrac{n}{p}$ ratio is high
  2. Low binding energy
  3. High packing fraction

Multiple choice chemistry the structure of the atom discovery of charged particles the plum pudding atom discovery of electrons and protons

The density of nucleus is of the order of:

  1. ${ 10 }^{ 5 }kg{ m }^{ -3 }$
  2. ${ 10 }^{ 10 }kg{ m }^{ -3 }$
  3. ${ 10 }^{ 17 }kg{ m }^{ -3 }$
  4. ${ 10 }^{ 25 }kg{ m }^{ -3 }$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The density of nucleus is about $2.3\times { 10 }^{ 17 }{ ㎏ }/㎥$. The density is same for all nuclei. Thus density of nucleus is of the order ${ 10 }^{ 17 }{ ㎏ }/㎥$