Tag: discovery of subatomic particles

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Multiple choice chemistry what is inside atom discovery of neutrons structure of atoms discovery of subatomic particles

Which of the following is the main cause of late discovery of neutron?

  1. Neutron is highly unstable particle

  2. Neutron in nucleus moves very fast

  3. Neutron is charge-less particle

  4. All of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Initially it was believed that the atom consisted of a small massive nucleus with positive charge surrounded by a much larger cloud of negatively charged electrons. Being charge-less particle, neutron did not show their influence in experiments performed for discovery of charged particles electrons and protons.

Multiple choice chemistry what is inside atom discovery of neutrons structure of atoms discovery of subatomic particles

Which of the following reactions led to the discovery of neutron?

  1. $ _6^{12}C+ _1^1H\rightarrow _7^{14}N+ _0^In$
  2. $ _{11}^{5}C+ _1^2D\rightarrow _{6}^{12}C+ _0^In$
  3. $ _4^{9}Be+ _2^4He\rightarrow _6^{12}C+ _0^1n$
  4. $ _4^{8}C+ _2^4He\rightarrow _6^{11}C+ _0^1n$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In 1930 it was discovered that Be bombarded by alpha particles and emitted stream of radiation. In 1932 Chadwick proposed that the particle is Rutherford's neutron.

$ _{ 2 }^{ 4 }{ \alpha  }+ _{ 4 }^{ 9 }{ Be }\rightarrow _{ 6 }^{ 12 }{ C }+ _{ 0 }^{ 1 }{ n }$

Multiple choice chemistry what is inside atom discovery of neutrons structure of atoms discovery of subatomic particles

A neutral atom of an element with nuclear charge 11 times and mass 23 times that of hydrogen. Find the ratio of electrons to protons present in its stable ion.

  1. 1:1

  2. 5:6

  3. 10:11

  4. 12:11
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Protons in neutral atom = nuclear charge = 11

Electrons in neutral atom = 11
Mass = 23 

Element = Sodium
Ion = $Na^+$
Electrons in ion = 11-1 = 10
Protons in ion = 11
Ratio of electron to proton = 10:11

Multiple choice chemistry what is inside atom discovery of neutrons structure of atoms discovery of subatomic particles

Chadwick was able to prove that:

  1. the radiation causing the ejected particles was much more energetic than could be accounted for by photons

  2. the radiation causing the ejected particles was much less energetic than could be accounted for by photons

  3. the radiation causing the ejected particles was much more energetic than could not be accounted for by photons

  4. the radiation causing the ejected particles was much less energetic than could not be accounted for by photons
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Chadwick was able to prove that the radiation causing the ejected particles was much more energetic than could be accounted for by photons. Initially it was though that the radiation must be gamma rays. But the radiations differed in interaction with hydrocarbons and with elements like helium, lithium, carbon, oxygen, nitrogen etc.

Multiple choice chemistry what is inside atom discovery of neutrons structure of atoms discovery of subatomic particles

What really occurred when one bombarded beryllium with alpha particles?

  1. Formation of a carbon-12 nucleus and the emission of a neutron

  2. Formation carbon-13 nucleus with the emission of a photon

  3. Formation carbon-14 nucleus with the emission of a photon

  4. Formation of a carbon-13 nucleus and the emission of a neutron
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When one bombarded beryllium with alpha particles, a carbon-12 nucleus was formed and a neutron was emitted.
$ _4^9Be + _2^4He \rightarrow _6^{12}C + _0^1n$

Multiple choice chemistry what is inside atom discovery of neutrons structure of atoms discovery of subatomic particles

Why did Chadwick thought that the emerging particles on radiations were not photons?

  1. Energy of the emerging particles was very low as compared to photon

  2. Energy of the emerging particles was equal to photon

  3. Energy of the emerging particles was much more than the photons

  4. None of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Chadwick carried out the experiments, using many different elements as radiation targets besides paraffin. By comparing the energies of particles ejected from all these various targets, Chadwick was able to prove that the radiation causing the ejected particles was much more energetic than could be accounted for by photons.