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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
Write the molecular formulae of Copper oxide.
Define of Molecular formula.
Write the molecular formulae for the following compounds and name the elements present of Baking soda.
Write the molecular formulae of Magnesium carbonate.
Write the chemical formula of the following compound in a step-by-step manner –
Sodium bromide
Write the chemical formula of the following compound in a step-by-step manner –
Potassium sulphate
Write the chemical formula of the following compound in a step-by-step manner –
Zinc hydroxide
Write the chemical formula of the following compound in a step-by-step manner –
Iron [III] oxide
Match the statements – 1 to 10 below with their correct answers from – A to J.
| Column I | Column II |
| 1. Elements having valency of two. | A: Br1− |
| 2. An anion | B: Divalent |
| 3. A gaseous non-metal | C: Reactants |
| 4. A cation. | D: Ammonium |
| 5. The term used for the substances which take part in the chemical reaction | E: Nitric oxide |
| 6. The meaning of the symbol ‘Δ’ over the arrow in a chemical equation. | F: Nitrogen |
| 7. The chemical name for nitrogen monoxide. | G: Zero |
| 8. A radical containing nitrogen and hydrogen only | H: Nitrous oxide |
| 9. The chemical name for dinitrogen oxide | I: Heat required |
| 10. The valency of noble gases | J: K1+ |
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 |
