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प्रश्न
Explain the Atomic number with example.
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उत्तर
- The number of protons present in the nucleus of an atom is called atomic number.
- It is denoted by Z.
- e.g., in `""_20^40Ca,` atomic number = 20
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संबंधित प्रश्न
The composition of the nuclei of two atomic species X and Y are given as under
| X | Y | |
| Protons | 6 | 6 |
| Neutrons | 6 | 8 |
Give the mass numbers of X and Y. What is the relation between the two species?
FILL IN THE BLANK
Atomic theory of matter was given by ..........................
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?
Give reason
Actual atomic mass is greater than mass number.
‘Valency is the number of hydrogen atoms which can combine with [or displace] one atom of the element [or radical] forming a compound’. With reference to the above definition of valency, state the valency of chlorine in hydrogen chloride, giving reasons.
Define the term of atomic number.
An element ‘A’ has mass number 23 and atomic number 11. State the –
- no. of neutrons in its shell,
- electronic configuration of the element ‘A’.
The ratio of the radii of hydrogen atom and its nucleus is ~ 105. Assuming the atom and the nucleus to be spherical,
- what will be the ratio of their sizes?
- If atom is represented by planet earth ‘Re ’ = 6.4 ×106 m, estimate the size of the nucleus.
‘Z’ is denoted by ______.
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.
