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Question
The atomic number and the mass number of sodium are 11 and 23 respectively. What information is conveyed by this statement.
Solution
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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| Atomic Number | Mass Number | Protons | Neutrons | Electrons | Symbol |
| 10 | 22 | _________ | _________ | _________ | _________ |
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(b) What is the relation between the atomic number and mass number of an element?
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| Column A | Column B | ||
| 1. | Mass of proton | a. | +1 |
| 2. | Mass of electron | b. | -1 |
| 3. | Charge of electron | c. | 9.31 x 10-28g |
| 4. | Charge of proton | d. | 1.67 x 10-24g |
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Boron, Aluminium, Gallium, Indium, Thallium
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