Q1 Give the list of changes,that …

Ans1. Digestion of food, process of photosynthesis, burning of fuel, cooking of food etc. Ans2. 1.Coating with oil,grease,paint. 2. Object not in contact of oxygen,water and moisture. 3. By the process of galvantion. The process of depositing a layer of zinc over object.

Answer 1 ? Change of odor. Change of color (for example, silver to reddish-brown when iron rusts). Change in temperature or energy, such as the production (exothermic) or loss (endothermic) of heat. Change of composition - paper turning to ash when burned. Answer 2 ? Here are some ways where we can prevent rusting : Paint it - Paint the metal with any durable acrylic paint. ...Keep moisture at Bay - Avoid contact with water or moisture. ...Coat it with Oil - Use of oil or grease significantly reduces the chances of developing rust in iron.

2. 

(1) Rusting of iron can be prevented by painting

When a coat of paint is applied to the surface of an iron object, then air and moisture cannot come in contact with the iron object and hence no rusting takes place. The window grills, railings, steel furniture, iron bridges, railway coaches, and bodies of cars, buses and trucks, are all painted regularly to protect them from rusting.

(2) Rusting of iron can be prevented by applying grease or oil

When some grease or oil is applied to the surface of an iron object, then air and moisture cannot come in contact with it and hence rusting is prevented.

The tools and machine parts made of iron and steel are smeared with grease or oil to prevent their rusting.

(3) Rusting of iron can be prevented by galvanisation

The process of depositing a thin layer (or coating) of zinc metal on iron objects is called galvanisation.

1. 

Examples of chemical changes :

Souring of milk
Formation of curd from milk
Cooking of food (like rice and chapatis)
Spoilage of food
Change in colour of cut apple (cut brinjal or cut potato) on keeping in air
Photosynthesis
Digestion of food
Neutralisation reaction
Explosion of a firework (or cracker)
Burning of magnesium ribbon
Burning of fuels (like burning of wood, coal, kerosene, LPG and biogas)
Burning of dry leaves
Burning of candle wax
Burning of incense stick
Rusting of iron
Ripening of fruits