Give reasons for the following observation: The smell of hot sizzling food reaches you several metres away. But to get the smell from cold food you have to go close.

Give reasons for the following observations (a) The smell of lighted incense stick spreads several metres away. (b) A liquid has a fixed volume but not a fixed shape. (c ) Ice floats over water.

Give reasons for the following observations (a) The smell of lighted incrense stick spreads several metres away. (b) A liquid has a fixed volume but not a fixed shape. (c ) Ice floats over water. (d) A wooden table is called a solid at room temperature.

Give reason for the following observations. (a) Naphthalene balls disappear with time without leaving any solid. (b) We can get the smell of perfume sitting several metres away.

Give reasons for the following: If there is a glass door and is closed then you may not be able to see it and get hurt if you try to paas through it.

When you smell a favourite food your month begins to water (that is, you secrete saliva). Write down that the following are examples of: (a) the smell of the food (b) the cells in your nasal passages which perceive the smell (c) the gland which is stimulated to stimulated to secrete saliva.

(a) When an incense stick (agarbatti) is lighted in one corner of a room, its fragrance quickly spreads in the entire room. Name the process involved in this. (b) A girl is cooking some food in the kitchen. The smell of food being cooked soon reaches her brother's room. Explain how the smell could have reached her brother's room.

Give reasons for the following : (i) The blue colour of copper sulphate solution is rendered light green when a piece of iron is dropped into it. (ii) Fried potato chips are often packed with nitrogen gas. (iii) Cooked food emits a bad smell when left exposed to air for a day or two.

Give reasons for the following : (i) Use of aspartame as an artificial sweetener is limited to cold foods. (ii) Metal hydroxides are better alternatives than sodiumk hydrogen carbonate for treatment of acidity. (iii) Aspirin is used in prevention of heart attacks.