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प्रश्न
The atomic number and the mass number of sodium are 11 and 23 respectively. What information is conveyed by this statement.
उत्तर
Atomic number = 11; No of protons = 11
Mass number = 23 = Number of protons + Number of neutrons.
No of neutrons = 23-11 = 12.
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संबंधित प्रश्न
(a) What is meant by (i) atomic number, and (ii) mass number, of an element? Explain with the help of an example.
(b) What is the relation between the atomic number and mass number of an element?
(c) If an element M has mass number 24 and atomic number 12, how many neutrons does its atom contain?
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Match the statements in List I with the correct answer from List II.
| List I | List II |
| 1. Mass number of an atom is the number of protons and | A: Electron |
| 2. The sub-atomic particle with a negligible mass. | B: Argon |
| 3. An atom having stable electronic configuration. | C: Nitrogen |
| 4. A molecule formed by sharing of electrons [covalency] | D: Sodium |
| 5. A metallic atom having unstable electronic configuration. | E: Neutrons |
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- forms anion – negative ion;
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- has 4 electrons in the outermost orbit. [Y, Z, X]
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Atomic number and mass number
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