Q22 of 33 Page 22

Give two methods to slow down rancidity.

Rancidity is the aerial oxidation of unsaturated fatty acids present in the food items. To prevent this oxidation following measures can be taken:

1. Keeping the food in air-tight containers


2. Packing the food at low temperatures


3. Addition of anti-oxidants to the food items.


4. Adding nitrogen gas during the packaging of food.


More from this chapter

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20

Observe the diagram given alongside and answer the following questions:


a. What do you observe when lead nitrate is heated?


b. Mention the two gases evolved equation for it.


c. Write the balanced chemical equation for it.


d. What is the type of chemical reaction called?


e. Give one more example of this type of reaction.

 21

You are provided with two containers made up of copper and aluminum. You are also provided with solutions of dilute HCl, dilute HNO3, ZnCl2, and H2O. In which of the above containers these solutions can be kept?

 22

(i) Define corrosion. Under what conditions does corrosion take place?

(ii) Give the formula and the chemical name of rust.

 23

Write balanced chemical equations for the following word equations:

(a) Calcium hydroxide + Carbon dioxide → Calcium carbonate + Water


(b) Phosphorus pentachloride + Water Phosphoric acid + Hydrogen chloride


(c) Zinc + Silver nitrate Zinc nitrate + Silver


(d) Sodium + water sodium hydroxide + Hydrogen


(e) Aluminium + Copper chloride Aluminium chloride + Copper