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प्रश्न
Give a reason why elements are tabulated in a table called the ‘Periodic table’.
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उत्तर
For arranging all the elements in a systematic and simple manner. The arrangement of elements was done in the form of a table called Periodic Table in which elements are arranged in increasing order of their atomic numbers. Elements in the Periodic Table are arranged in Horizontal rows called Periods and vertical columns called groups. Metallic elements are placed on the left non-metallic on the right and noble gases on the extreme right of the Periodic table.
संबंधित प्रश्न
Give the symbols and valencies of following radicals:
(a) Hydroxide (b) Chloride
(c) Carbonate (d) ammonium
(e) Nitrate
Explain the significance of the symbol H.
Match the non-metallic elements – with their correct symbols. Non-metallic elements are:
| Non-Metallic elements | Symbol |
| (a) Carbon | (1) O |
| (b) Chlorine | (2) I |
| (c) Oxygen | (3) Si |
| (d) Phosphorus | (4) C |
| (e) Hydrogen | (5) Cl |
| (f) Nitrogen | (6) P |
| (g) Iodine | (7) F |
| (h) Bromine | (8) H |
| (i) Fluorine | (9) S |
| (j) Silicon | (10) Br |
| (k) Sulphur | (11) N |
Give the names and symbols of the first twenty elements of the periodic table.
Give the symbol of the following element:
Oxygen
State the type of element for the following:
Sulphur
State the type of element for the following:
Silicon
State whether the following ion or radical given below of a non-metallic element exhibits valency: 1–, 2– or 3–. (write the ion or radical with the correct valency).
Iodide
What does the symbol '(l)' present in a chemical equation, mean?
How many elements are known at present?
