Tag: structure of atoms

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

The triad of nuclei that is isotonic is :

  1. $^{14} _6C,\,^{15} _7N,\, ^{17} _9F$
  2. $^{12} _6C,\,^{14} _7N,\, ^{19} _9F$
  3. $^{14} _6C,\,^{14} _7N,\, ^{17} _9F$
  4. $^{14} _6C,\,^{14} _7N,\, ^{19} _9F$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The triad of nuclei that is isotonic is  $^{14} _6C,\,^{15} _7N,\, ^{17} _9F$.
Number of neutrons are
$C -14-6=8$
$N-15-7=8$
$F-17-9=8$

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

The atoms of different elements having the same number of neutrons are known as :

  1. isobars

  2. isomers

  3. isotones

  4. isotopes
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Two nuclides are isotones if they have same neutron number but different proton number e.g. $boron-12$ and $carbon-13$ both contain 7 neutrons so they are $isotones$.

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

The nuclides $^{40} _{18}Ar$ and $^{41} _{19}K$ are :

  1. isotopes

  2. isobars

  3. isotones

  4. none of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The two or more species of atoms or nuclei that have the same number of neutrons are called as isotones.


The nuclides $^{40} _{18}Ar$ and $^{41} _{19}K$ are isotones. Because they have the same number of neutron.

So, the correct option is $C$

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

Density of neutron is of the order of :

  1. $10^3 kg/cc$
  2. $10^6 kg/cc$
  3. $10^{12} kg/cc$
  4. $10^2 kg/cc$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

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

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

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

  1. 4

  2. 2

  3. 8

  4. 6
Reveal answer Fill a bubble to check yourself
B Correct answer
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. $4-2.$

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

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

  1. 4

  2. 12

  3. 8

  4. 6
Reveal answer Fill a bubble to check yourself
B Correct answer
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. $6 + 6=12$.

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

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

  1. 4

  2. 12

  3. 8

  4. 6
Reveal answer Fill a bubble to check yourself
C Correct answer
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. $16-8$.

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

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

  1. Neutron

  2. Hydrogen molecule

  3. Alpha particle

  4. Positron

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