Question

Name the different types of pure substances?​

Answer 1

Explanation:

Examples of pure substances include tin, sulfur, diamond, water, pure sugar (sucrose), table salt (sodium chloride) and baking soda (sodium bicarbonate). Crystals, in general, are pure substances. Tin, sulfur, and diamond are examples of pure substances that are chemical elements

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Answer 2

Answer:

Valency is defined as the combining capacity of the element. It is determined by the number of valence shell electrons present in the atom.  

If the number of valence electrons is less than or equal to 4 so the valency is the same as the number of electrons present.  

If the number of valence electrons is more than 4 then the valency is 8-(the number of valence shell electrons).

Example:

(1)Silicon has atomic number 14. The electronic configuration of silicon is 2, 8, 4. The number of valence electrons is 4. So the valency is 4.

(2)Oxygen has an atomic number 8. The electronic configuration is 2, 6. The valency is (8-6)=2