Tag: discovery of subatomic particles

Questions Related to discovery of subatomic particles

Who determined the mass of a neutron?

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

  1. John Dalton (early 1800's)

  2. Ernest Rutherford (1911)

  3. Niels Bohr (1913)

  4. James Chadwick (1932)

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Correct Option: D
Explanation:

The presence of neutron and its mass was determined by James Chadwick. Neutron was discovered by bombarding $\alpha-$particles on $Be$. On doing so, highly energetic beam of radiation was observed by Chadwick. Thus mass of neutron was determined by James Chadwick.

Whose experiment proved the existence of the nucleus?

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

  1. John Dalton (early 1800's)

  2. Ernest Rutherford (1911)

  3. Niels Bohr (1913)

  4. James Chadwick (1932)

Show answer
Correct Option: B
Explanation:

The $\alpha-$ ray scattering-gold foil experiment by Ernest Rutherford gave substantial evidence for  existence of nucleus in $1911$. Thus the existence of nucleus was proved by Rutherford's experiment.

Neutron was discovered by:

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

  1. J.J. Thomson

  2. Chadwick

  3. Rutherford

  4. Priestley

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Correct Option: B
Explanation:

 Neutron was discovered by Chadwick.
To overcome the failure of proton electron hypothesis, Rutherford, in 1920, proposed the existence of neutral particle made from close combination of proton and electron. He named it neutron.
In 1932, Lord Chadwick proved the existence of neutron by bombarding lighter elements (boron and beryllium) with alpha particles which resulted in the emission of highly penetrating neutral radiation.

The neutron is a neutral (non-electrical) particle in the centre of the atom. It was discovered when a tiny piece of the metal, beryllium, was bombarded with alpha particles. This discovery was made by:

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

  1. Chadwick

  2. Rutherford

  3. Niels Bohr

  4. Enrico Fermi

Show answer
Correct Option: A
Explanation:
In 1930, it was discovered that Beryllium, when bombarded by alpha particles, emitted a very energetic stream of neutral radiation. In 1932, Chadwick proposed that neutral radiation consists of a new type of neutral particles - neutrons.

An αα particle is:

chemistry atom fundamental particles of an atom the structure of atoms discovery of subatomic particles

  1. a hydrogen molecule

  2. a helium nucleus

  3. an electron

  4. a proton

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Correct Option: B
Explanation:

$(B)$ a helium nucleus 


$Reason$ : An $\alpha$ particle is a positively charged particle consists of two protons and two neutrons , all held together by the same strong nuclear force that binds the nucleus of any atom , emitted by some radioactive substances and identical to the nucleus of helium atom . It carry a charge of $+2$. 

What makes the atom of one element different from another element's atom ?

chemistry atom fundamental particles of an atom the structure of atoms discovery of subatomic particles

  1. Number of protons

  2. Number of electrons

  3. Number of neutrons

  4. Number of ions

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Correct Option: A
Explanation:

The number of protons in an atom determines what element you have. For instance hydrogen has one proton, carbon has six.

If number of electrons in an atom is 8 and number of protons is also 8, then give the atomic number of atom and the charge on the atom.

chemistry atom fundamental particles of an atom the structure of atoms discovery of subatomic particles

  1. (i) Atomic number = 8, (ii) Charge = 0

  2. (i) Atomic number = 4, (ii) Charge = 0

  3. (i) Atomic number = 8, (ii) Charge = +1

  4. (i) Atomic number = 4, (ii) Charge = +1

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Correct Option: A
Explanation:

Atomic number is equal to number of protons i.e. 8. Since number of protons is equal to number of electrons i.e. 8, therefore charge on the atom is 0.

The charge on a proton is ___________.

chemistry atom fundamental particles of an atom the structure of atoms discovery of subatomic particles

  1. $-1602\times10^{-19}C$

  2. $1.602\times10^{-19}C$

  3. $0$

  4. None of the above

Show answer
Correct Option: B
Explanation:

The charge on protons is equal to $1.602\times10^{-19}C$

Elements are defined by the number of _______ they possess.

chemistry atom fundamental particles of an atom the structure of atoms discovery of subatomic particles

  1. electrons

  2. protons

  3. neutrons

  4. atoms

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Correct Option: B
Explanation:

Elements are defined by the number of protons they possess.

Absolute mass of a proton is equal to __________.

chemistry atom fundamental particles of an atom the structure of atoms discovery of subatomic particles

  1. $9.109\times10^{-31}$ kg

  2. $-1.602\times10^{-31}$ kg

  3. $1.672\times10^{-27}$ kg

  4. $1.674\times10^{-27}$ kg

Show answer
Correct Option: C
Explanation:

The mass of proton is equal to $1.672\times10^{-27}$ kg.


Hence the correct option is C.