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प्रश्न
What is variable valency ? Give two examples of elements showing variable valency.
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उत्तर
Certain elements exhibit more than one valency, that means they show variable valency.
Ferrous is written as Iron (II) and Ferric is written as Iron (III).
| Metal | Radicals | Valency |
| Iron | Ferrous [Iron (II)] Ferric [Iron (III)] |
2 3 |
| Copper | Cuprous [Copper (I)] Cupric [Copper (II)] |
1 2 |
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संबंधित प्रश्न
Define of Molecular formula.
The valency of aluminium is 3. Write the valency of other radicals present in the following compounds of Aluminium oxide.
The valency of aluminium is 3. Write the valency of other radicals present in the following compounds of Aluminium nitride
The valency of aluminium is 3. Write the valency of other radicals present in the following compounds of Aluminium sulphate.
A solution of a substance ‘X’ is used for white washing.
(a) Name the substance ‘X’ and write its formula.
(b) Write the reaction of the substance ‘X’ named in (a) above with water.
Write the molecular formulae of Iron (III) chloride
Write the chemical formula of the following compound in a step-by-step manner –
Sodium bisulphate
Write the chemical formula of the following compound in a step-by-step manner –
Potassium dichromate
Write the chemical formula of the following compound in a step-by-step manner –
Aluminium hydroxide
Match the compounds in List I – 1 to 20 with their correct formulas in List II – A to T.
| List I | List II |
| 1. Copper [I] sulphide | A: KMnO4 |
| 2. Potassium permanganate | B: Mg3N2 |
| 3. Phosphoric acid | C: Mg(NO3)2 |
| 4. Copper [I] oxide | D: Al2(SO4)3 |
| 5. Carbonic acid | E: Na2ZnO2 |
| 6. Aluminium sulphide | F: N2O |
| 7. Iron [II] oxide | G: H2CO3 |
| 8. Iron [III] sulphide | H: Al2S3 |
| 9. Iron [II] sulphate | I: NO |
| 10. Sodium zincate | J: FeS |
| 11. Nitrous oxide | K: Fe2S3 |
| 12. Aluminium sulphate | L: H3PO4 |
| 13. Magnesium nitride | M: Cu2S |
| 14. Iron [III] sulphate | N: CuS |
| 15. Copper [II] oxide | O: Fe2O3 |
| 16. Iron [III] oxide | P: FeO |
| 17. Nitric oxide | Q: FeSO4 |
| 18. Copper [II] sulphide | R: Fe2(SO4)3 |
| 19. Iron [II] sulphide | S: CuO |
| 20. Magnesium nitrate | T: Cu2O |
