Tag: discovery of charged particles

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Questions Related to discovery of charged particles

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 ${ 10 }^{ 17 }{ ㎏ }/㎥$

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

The radius of nucleus is:

  1. proportional to its mass number

  2. inversely proportional to its mass number

  3. proportional to the cube root of its mass number

  4. not related to its mass number
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
The radius of a nucleus (r) is proportional to the cube root of its mass number (A).
The approximate law is $r = r _0 \times A^{ 1/3 }$
where $r _0 = 1.2 \times 10^{ -15 }\ m$
option C is correct