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प्रश्न
With the help of given Table, find out the mass number of oxygen.
| Composition of Atoms of the First Eighteen Elements with Electron Distribution in Various Shells | ||||||||||
| Name of Element | Symbol | Atomic Number | Number of protons | Number of Neutrons | Number of Electrons | Distribution of Electrons | Valency | |||
| K | L | M | N | |||||||
| Hydrogen | H | 1 | 1 | - | 1 | 1 | - | - | - | 1 |
| Helium | He | 2 | 2 | 2 | 2 | 2 | - | - | - | 0 |
| Lithium | Li | 3 | 3 | 4 | 3 | 2 | 1 | - | - | 1 |
| Beryllium | Be | 4 | 4 | 5 | 4 | 2 | 2 | - | - | 2 |
| Boron | B | 5 | 5 | 6 | 5 | 2 | 3 | - | - | 3 |
| Carbon | C | 6 | 6 | 6 | 6 | 2 | 4 | - | - | 4 |
| Nitrogen | N | 7 | 7 | 7 | 7 | 2 | 5 | - | - | 3 |
| Oxygen | O | 8 | 8 | 8 | 8 | 2 | 6 | - | - | 2 |
| Fluorine | F | 9 | 9 | 10 | 9 | 2 | 7 | - | - | 1 |
| Neon | Ne | 10 | 10 | 10 | 10 | 2 | 8 | - | - | 0 |
| Sodium | Na | 11 | 11 | 12 | 11 | 2 | 8 | 1 | - | 1 |
| Magnesium | Mg | 12 | 12 | 12 | 12 | 2 | 8 | 2 | - | 2 |
| Aluminium | Al | 13 | 13 | 14 | 13 | 2 | 8 | 3 | - | 3 |
| Silicon | Si | 14 | 14 | 14 | 14 | 2 | 8 | 4 | - | 4 |
| Phosphorus | P | 15 | 15 | 16 | 15 | 2 | 8 | 5 | - | 3.5 |
| Sulphur | S | 16 | 16 | 16 | 16 | 2 | 8 | 6 | - | 2 |
| Chlorine | Cl | 17 | 17 | 18 | 17 | 2 | 8 | 7 | - | 1 |
| Argon | Ar | 18 | 18 | 22 | 18 | 2 | 8 | 8 | 0 | |
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उत्तर
The number of protons and neutrons present in the nucleus of an atom is called mass number.
That is, mass number = number of protons + number of neutrons
Mass number = 8 + 8
= 16
Sulfur protons = 16, neutrons = 16
Mass number = 16 + 16
= 32
संबंधित प्रश्न
What are the atomic numbers of elements whose outermost electrons is represented by 3s1.
Multiple Choice Questions
The sum of number of protons and number of neutrons present in the nucleus of an atom is called its
In group I of the periodic table, three elements X, Y, and Z have ionic radii 1.33 Å, 0.95 Å and 0.60 Å respectively. Giving a reason, arrange them in the order of increasing atomic number in the group.
Fill in the following blanks in respect of an atom of an element
| No. of protons | No. of neutron | Mass number | Atomic number | No. of electrons | Symbol |
| 11 | 12 | ___________ | ___________ | ___________ | ________ |
The diagram represents an isotope of hydrogen [H]. Answer the following:
Atomic no. = 1
Mass no. = 1
Are isotopes atoms of the same element or different elements.
The diagram represents an isotope of hydrogen [H]. Answer the following:
Atomic no. = 1
Mass no. = 1
If an isotope of ‘H’ has mass no. = 2, how many electrons does it have.
The diagram represents an isotope of hydrogen [H]. Answer the following:
Atomic no. = 1
Mass no. = 1
Which sub-atomic particles in the 3 isotopes of ‘H’ are the same.
Draw the structure of the following atoms showing the nucleus containing – protons, neutrons and the orbits with the respective electron:
Lithium [At. no. = 3, Mass no. = 7]
Which of the following are true for an element?
- Atomic number = number of protons + number of electrons
- Mass number = number of protons + number of neutrons
- Atomic mass = number of protons = number of neutrons
- Atomic number = number of protons = number of electrons
Name the 3 sub-atomic particles of an atom.
