Viva Voce: Types of Reactions | Lab Manuals for Class 10 PDF Download

Q.1. What is calcium oxide commonly called?

Calcium oxide (CaO) commonly known as quicklime.

Q.2. A small amount of quicklime is taken in a beaker. Water is added slowly to the beaker. What observation would you note down?

When water is added slowly in a quicklime, hissing sound is produced and the solution becomes hot.

Q.3. Why should we not touch iron container in which CaO reacts with H₂O?

We should not touch iron container in which CaO reacts with H₂0 because iron container will be very hot as the reaction is exothermic.

Q.4. What is the effect of temperature on the solubility of calcium hydroxide?

Solubility of calcium hydroxide or slaked lime decreases with increase in temperature.

Q.5. Name the chemical formula and chemical name of slaked lime.

Chemical formula of slaked lime - Ca(OH)₂
Chemical name of slaked lime - Calcium hydroxide

Q.6. Give an example of a combination reaction.

When magnesium ribbon burns in air, it forms magnesium oxide. This is an example of combination reaction.

Q.7. What is the suspension of slaked lime in water commonly called?

The suspension of slaked lime in water is commonly called milk of lime.

Q.8. Avinav takes 2 mL of clear liquid from the mixture of quicklime with water and then he breath out in it. What would he observed?

The filtrate turns milky.

Q.9. Out of CuO, Na₂O, CaO and P₂O₅, in which oxide solution, lime water is formed when water is mixed?

When water is mixed with CaO, lime water is formed

Q.10. Why lime water turns milky when CO₂ gas is passed through a test tube containing lime water?

Lime water turns milky due to the formation of insoluble precipitate of calcium carbonate (CaCO₃).

Q.11. When slaked lime is brought in contact with red litmus paper, what do you observe?

We observe that red litmus paper turns blue. From this, we can conclude that slaked lime is basic in nature.

Q.12. How is lime water prepared?

Mix calcium oxide with water, shake the mixture well and leave it to stand for a while. Collect the clean solution on top. This is lime water.

Q.13. Most of the combination reactions are exothermic in nature. Give reason.

Most of the combination reactions are accompanied by liberation of heat energy. This is known as exothermicity. For example, when natural gas burns in the oxygen of air, it forms carbon dioxide and water vapour. A large amount of heat is also produced.

Q.14. Is the reaction between quicklime and water exothermic or endothermic?

As heat energy is released during the reaction, therefore it is an exothermic reaction.Q.15.

Q.15. Write the product formed when quicklime reacts with water.

Quicklime reacts with water to give calcium hydroxide Ca(OH)₂, ie. slaked lime.
CaO+ H₂O → Ca(OH)₂

Q.16.  Name the reaction between calcium oxide and water.

The reaction between calcium oxide and water is known as combination reaction.

Q.17. What is combination reaction?

A reaction in which two or more substances combine to form a single product (compound) is called a combination reaction.