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प्रश्न
Differentiate mass number from atomic number.
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उत्तर
| Sr. No. | Atomic number | Mass number |
| 1. | The number of electrons or protons in an atom is called atomic number of that atom. | The number of protons and neutrons present is its nucleus is called mass number of that atom. |
| 2. | It is represented by the letter Z | It is represented by the letter ‘A’. |
| 3. | Example: Helium (He) has 2 protons and two electrons hence its atomic number will be 2. | Example: Sodium (Na) has 11 protons and 12 Neutrons hence its mass number A= 11 + 12 = 23 |
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संबंधित प्रश्न
Complete the following table.
| Atomic number | Mass number | Number of Neutrons | Number of protons | Number of electrons | Name of the Atomic species |
| 9 | - | 10 | - | - | - |
| 16 | 32 | - | - | - | Sulphur |
| - | 24 | - | 12 | - | - |
| - | 2 | - | 1 | - | - |
| - | 1 | 0 | 1 | 0 | - |
Multiple Choice Questions
If the atomic number of an atom is 17 and mass number is 35 then number of neutron will be
State the mass number, the atomic number, number of neutrons and electronic configuration of the following atoms.
`""^12""_6C, ""^16""_8O, ""^19""_9F, ""^20""_10Ne, ""_13""Al""^27, ""_17""Cl""^35`
Also, draw atomic diagrams for them.
From the symbol `""_15^31"P"`, state :
(i) mass number of phosphorus,
(ii) atomic number of phosphorus, and
(iii) electron configuration of phosphorus.
An element A atomic number 7 mass numbers 14
B electronic configuration 2,8,8
C electrons 13, neutrons 14
D Protons 18 neutrons 22
E Electronic configuration 2,8,8,1
State Valency of each element
An element A atomic number 7 mass numbers 14
B electronic configuration 2,8,8
C electrons 13, neutrons 14
D Protons 18 neutrons 22
E Electronic configuration 2,8,8,1
State (i) Valency of each element (ii) which one is a metal (iii) which is non-metal (iv) which is an inert gas
If an atom ‘A’ has atomic number 19 and mass number 39, state –
- Its electronic configuration.
- The number of valence electrons it possesses.
Atomic number : ______ :: Mass number : Number of protons and neutrons.
The Atomic number of an element is 20. It has ______ valence electrons.
Electrons revolve around the nucleus in definite open shells.
Element ‘P' has electronic configuration 2,8,8,1. The number of chlorine atoms present in the chloride of ‘P’ is ______.
