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प्रश्न
Explain the terms 'valency' and 'variable valency'.
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उत्तर
Valency: The number of electrons that an atom can lose, gain or share during a chemical reaction is called its valency.
Variable valency: Certain elements exhibit more than one valency, i.e. they show variable valency.
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संबंधित प्रश्न
Write the names and symbols of the first twenty elements that you have studied in class VI & VII.
Give two symbols which have been derived from the "English names" of the elements.
Give the names and symbols of five familiar substances which you think are elements.
For writing a chemical formula – ‘symbols’ and combining capacity of an element with hydrogen i.e. ‘valency’ should be known. Explain the term – combining the capacity of an element i.e. valency.
Match the symbols of non-metallic elements with their correct combining power or capacity.
(a) O
(b) S
(c) Cl
Combining power or capacity A : 3; B : 2; C : 1. (negative valencies)
Select the correct answer from the choice given below.
The type of element-phosphorus
State the type of element for the following:
Fluorine
Give the symbol of the following element:
Nitrate
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).
Chloride
How many elements are known at present?
