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प्रश्न
From the symbol `""_2^4"He"` for the element helium, write down the mass number and the atomic number of the element.
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उत्तर
Atomic number = 2
Mass number = 4
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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 | - |
What is variable valency? Name two elements having variable valency and state their valencies.
The mass number of an element is 23 and it contains 11 electrons. What is the number of protons and neutrons in it? What is the atomic number of the element?
From the symbol `""_15^31"P"`, state :
(i) mass number of phosphorus,
(ii) atomic number of phosphorus, and
(iii) electron configuration of phosphorus.
An atom of an element has two electrons in the M shell.
What is the (a) atomic number (b) number of protons in this element?
Match the atomic numbers 4,8,10,15 and 19 with the following:
Element with four shells
Draw the atomic diagram of the following element showing the distribution of – protons, neutrons and the electrons in the various shell of the atom.
Argon – \[\ce{^40_18Ar}\]
[The upper number represent the – mass number and the lower number represent the – atomic number e.g. calcium – mass number = 40, atomic number = 20]
Draw the structure of the following atoms showing the nucleus containing – protons, neutrons and the orbits with the respective electron:
Silicon [At. no. = 14, Mass no. = 28]
Complete the following table.
| Atomic Number | Mass Number | Number of Neutrons | Number of Protons | Number of Electrons | Name of the Element |
| 9 | ______ | 10 | ______ | ______ | ______ |
| 16 | ______ | 16 | ______ | ______ | ______ |
| ______ | 24 | ______ | ______ | 12 | Magnesium |
| ______ | 2 | ______ | 1 | ______ | ______ |
| ______ | 1 | 0 | 1 | 1 | ______ |
Ca2+ has completely filled outer shell. Justify your answer.
