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

Who determined the mass of a neutron?

  1. John Dalton (early 1800's)

  2. Ernest Rutherford (1911)

  3. Niels Bohr (1913)

  4. James Chadwick (1932)
Reveal answer Fill a bubble to check yourself
D Correct answer
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.

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

Whose experiment proved the existence of the nucleus?

  1. John Dalton (early 1800's)

  2. Ernest Rutherford (1911)

  3. Niels Bohr (1913)

  4. James Chadwick (1932)
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

Neutron was discovered by:

  1. J.J. Thomson

  2. Chadwick

  3. Rutherford

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

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

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:

  1. Chadwick

  2. Rutherford

  3. Niels Bohr

  4. Enrico Fermi
Reveal answer Fill a bubble to check yourself
A Correct answer
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.
Multiple choice chemistry atom fundamental particles of an atom the structure of atoms discovery of subatomic particles

An αα particle is:

  1. a hydrogen molecule

  2. a helium nucleus

  3. an electron

  4. a proton
Reveal answer Fill a bubble to check yourself
B Correct answer
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 $+2$. 

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

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.

  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
Reveal answer Fill a bubble to check yourself
A Correct answer
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.