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प्रश्न
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?
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उत्तर
Number of electrons in the M shell = 2
So, the number of electrons in the K and L shells will be = 2, 8
Hence, atomic number = 2 + 8 + 2 = 12
Number of protons = 12
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संबंधित प्रश्न
FILL IN THE BLANK
Atomic theory of matter was given by ..........................
TRUE \ FALSE
After the emission of a beta-particle, the atomic number of the atom increases by one.
Fill in the blank of the following statement :
The total number of protons and neutrons in the nucleus of an atom is called its _________.
(a) Which of the nuclear particles is present in the same fixed number in the atoms of any particular element?
(b) What do we call this number which is characteristic of a particular element?
Elements X, Y and Z have atomic numbers 6, 9 and 12 respectively. Which one:
- Forms an anion
- Forms a cation
- Has four electrons in its valence shell?
If an atom ‘A’ has mass number 35 and atomic number 17, state the number of protons, electrons and neutrons it contains.
Differentiate between the following term:
Atomic number and mass number
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 | ______ |
______ = No. of protons = No. of the electrons.
State the term for the following:
The amount of substance which contains the same number of units as the number of atoms in carbon-12.
