Tag: neutrons

Questions Related to neutrons

$ _7N^{15}$ and $ _8O^{16}$ are a pair of :

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

  1. isotopes

  2. isobars

  3. isotones

  4. none of them

Show answer
Correct Option: C
Explanation:

Two nuclides are isotones if they have the very same neutron number but different proton number.

Density of neutron is of the order of :

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

  1. $10^3 kg/cc$

  2. $10^6 kg/cc$

  3. $10^{12} kg/cc$

  4. $10^2 kg/cc$

Show answer
Correct Option: C
Explanation:

$Atomic\quad radius\quad of\quad neutron\quad =\quad { 10 }^{ -13 }cm\ mass\quad of\quad neutron\quad =\quad 1.6749\times { 10 }^{ -27 }kg\ density\quad of\quad neutron\quad =\quad \dfrac { Mass }{ Volume } =\quad { 10 }^{ 12 }\quad kg/cc$

Helium atom has an atomic mass of 4 u and two protons in its nucleus. How many neutrons does it have?

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

  1. 4

  2. 2

  3. 8

  4. 6

Show answer
Correct Option: B
Explanation:

Helium has 2 neutrons. The mass of an atom is given by the sum of the masses of protons and neutrons present in the nucleus. Since, the number of protons present in helium is 2 and given mass is 4. Therefore, the number of neutrons will be equal to $2$ i.e. $4-2.$

Carbon has six protons and six neutrons in its nucleus. What is the atomic mass of carbon?

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

  1. 4

  2. 12

  3. 8

  4. 6

Show answer
Correct Option: B
Explanation:

The atomic mass of carbon is $12$. The mass of an atom is given by the sum of the masses of protons and neutrons present in the nucleus. Since, the number of protons and neutrons present in carbon is $6$.
Therefore, the atomic mass of carbon is $12$ i.e. $6 + 6=12$.

Oxygen atom has an atomic mass of 16 u and eight neutrons in its nucleus. What is its atomic number?

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

  1. 4

  2. 12

  3. 8

  4. 6

Show answer
Correct Option: C
Explanation:

The atomic number of oxygen is 8. The mass of an atom is given by the sum of the masses of protons and neutrons present in the nucleus. Also, atomic number is the number of protons present in the nucleus. Since, the number of neutrons present in oxygen is 8 and given mass is 16. Therefore, the number of neutrons will be equal to $8$ i.e. $16-8$.

Which of the following particle has mass closest to the mass of a proton?

chemistry structure of the atom neutrons discovery of neutrons structure of atoms

  1. Neutron

  2. Hydrogen molecule

  3. Alpha particle

  4. Positron

  5. Electron

Show answer
Correct Option: A
Explanation:

Neutron has closest mass to a proton. The mass of proton and neutron are 1.0073 amu and 1.0087 amu respectively. Mass of electron is much lower than that of proton and neutron

Statement 1: Neutrons and protons are classified as nucleons.
Statement 2: Neutrons and protons are both located in the principal energy levels of the atom.

chemistry structure of the atom neutrons discovery of neutrons structure of atoms

  1. Both Statement 1 and Statement 2 are correct and Statement 2 is the correct explanation of Statement 1.

  2. Both Statement 1 and Statement 2 are correct and Statement 2 is not the correct explanation of Statement 1.

  3. Statement 1 is correct but Statement 2 is not correct.

  4. Statement 1 is not correct but Statement 2 is correct.

  5. Both the Statement 1 and Statement 2 are not correct.

Show answer
Correct Option: C
Explanation:
A nucleon is a collective name for two important subatomic particles: neutrons and protons. A nucleon is one of either of the two types of subatomic particles (neutrons and protons) which are located in the nucleus of atoms.
electrons are located in the principal energy levels of the atoms so statement 2 is not correct because neutron and proton stay in the nucleus of an atom.

The ratio of neutrons in ${O}^{16}$ and ${O}^{18}$ is

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

  1. $8 : 10$

  2. $4 : 5$

  3. $9 : 8$

  4. $1 : 1$

Show answer
Correct Option: A,B
Explanation:

 The ratio of neutrons in $\displaystyle {O}^{16}$ and $\displaystyle {O}^{18}$ is $\displaystyle 4 : 5 \text { or } 8 : 10$
Number of neutrons in $\displaystyle {O}^{16} = 16-8=8$
Number of neutrons in $\displaystyle {O}^{18}=18-8=10$

Which of the following atoms contains the least number of neutrons?  

chemistry structure of the atom neutrons discovery of neutrons structure of atoms

  1. $ _{92}^{235}{U}$

  2. $ _{92}^{238}{U}$

  3. $ _{93}^{239}{Np}$

  4. $ _{93}^{240}{Np}$

Show answer
Correct Option: A
Explanation:

 The number of neutrons is the difference between the mass number and atomic number.
   
$\displaystyle _{92}^{235}{U}$ contains the least number of neutrons

The number of neutrons in $\displaystyle _{92}^{235}{U}$ $\displaystyle = 235-92=143$

The number of neutrons in $\displaystyle _{92}^{238}{U} $ $\displaystyle =238-92=146$

The number of neutrons in $\displaystyle _{93}^{239}{Np}$ $\displaystyle = 239-93=146$

The number of neutrons in  $\displaystyle _{93}^{240}{Np}$ $\displaystyle =240-93=147$

The discovery of neutron came very late because:

chemistry structure of the atom neutrons discovery of neutrons structure of atoms

  1. it is present in nucleus

  2. it is a fundamental particle

  3. it does not move

  4. it does not carry any charge

Show answer
Correct Option: D
Explanation:

The discovery of neutron came very late because it does not carry any charge.

Neutron was discovered by Chadwick.


To overcome the failure of proton-electron hypothesis, Rutherford, in 1920, proposed the existence of neutral particle made from a close combination of proton and electron. He named it a 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.

Hence, the correct option is $\text{D}$.