Question of Chemistry

Q-3. * Because the perfumed incense is in solid state and by lighting of it, it changes from solid state to gaseous state the moment it turns in to gaseous state and gases have a property to spread in all directions.
After lightening the incense the molecules of perfume are in a gaseous state and mixing with the molecules of air in the room. All of them undergo random motion at all times as a result of the internal ("heat") energy that they have absorbed. The molecules often bump into each other, which causes them to mix if they were not mixed previously.
Q-4. How does the diffusion of Honey vary with the diffusion of ink?why?
Ink diffuses at a faster rate as compared to honey. This can be explained taking in to account that honey is a more viscous liquid as compared to ink. Therefore the low viscosity of ink allows it to diffuse at a faster rate than honey in a solution.
Q-9 Name two gases of air which dissolve in water by diffusion. What is the importance of this process in nature ?
Carbon-di-oxide and Oxygen are the two atmospheric gases, that can diffuse in water.
Oxygen is helpful for the animals inside the water and CO2 is helpful for plants in the water
The oxygen from lungs diffuses into the blood stream, and reaches our cells. Fishes are able breathe under water due to diffusion of dissolved oxygen in water, in their lungs.
Q-18 Why do gases have neither fixed shape nor fixed volume ? for volume.
This is because of the fact that the intermolecular forces between the gases are very weak. Therefore the molecules of the gases are moving randomly and freely in all the directions.The container in which gases are kept can fill the whole volume of the container irrespective of the shape of the container because the molecules randomly dispersed in all the directions. That is why gases do not have fixed volume and shape.
Q-20 explain why steam at 100 degree celcius ia better for heating purpose that boliling ater at 100 degrees
Steam has more energy than boiling water. It possesses the additional latent heat of vaporization. Therefore, steam at 1000 C is better for heating purposes than boiling water.
Q-24 How does perspiration help to keep our body cool on a hot day?
It is based on the fact that evaporation causes cooling. This is similar to the cooling of water kept in a mud pot in summer. There are many small holes in our whole body (our body is porous) the water that we drink comes out of these small holes and when the air touches the water droplets in the surface of our skin the water absorbs the heat on the surface of our skin and thus makes our body cool.

Q-26 Why do wet clothes dry more quickly when spread in the sun?
It is because of evaporation of water from clothes. Water can evaporate at room temperature. In dry, hot condition the process of evaporation is faster. Also, evaporation increases with increase in surface area. So, when we hang our clothes and spread it, it will get dry soon. Also, Evaporation increases with increase in velocity of wind.