NCERT Solutions for Class 9 Science Chapter 1 Matter in Our Surroundings in Hindi PDF Download
FAQs on NCERT Solutions for Class 9 Science Chapter 1 - In Hindi
1. A diver can cut through water in a swimming pool. Which property of matter does this observation show?
A diver can easily dive into the water of a swimming pool because the arrangement of molecules in a liquid (water in this case) is not compact, which increases the intermolecular space. Liquids like water also show a weaker force of attraction between the molecules which is also a cause of increased intermolecular space in liquids. Due to the high intermolecular space in the water, a diver can cut through the water.
2. Liquids generally have a lower density as compared to solids. But you must have observed that ice floats on water. Why?
If an object has a lower density than the density of a liquid, the object will float on the liquid. Solids have a higher density than liquids and that is precisely why solids float on water. But, ice is also solid, so it should float on water. But this is not the case because there are larger intermolecular spaces in ice as compared to water and that is why the density of ice is lower than the density of water. For more solutions from this chapter, visit the page NCERT Solutions for Class 9 Science Chapter 1 on the Vedantu website or download the Vedantu app to access these resources at free of cost.
3. What are the factors affecting evaporation?
Evaporation is a phenomenon in which a liquid changes into vapour at a temperature below its boiling point. Some factors affecting the evaporation are -
An increase in surface area will lead to an increase in the rate of evaporation
An increase in temperature increases the kinetic energy in liquid particles increasing evaporation.
Decrease in humidity: If moisture in the air is high, the rate of evaporation slows down.
An increase in wind speed helps in decreasing the amount of moisture in the air.
4. How does evaporation cause cooling?
Evaporation causes cooling because when evaporation occurs the particles that are losing energy during the process tries to gain back energy from the particles around it. This absorption of energy from the near surroundings causes a cooling effect on the surrounding from where the energy is being absorbed. One example is the use of acetone on your palm. When you are applying the acetone, the particles of the liquid absorb energy from its surroundings and evaporate giving a cooling sensation. For more Solutions from this chapter, visit the page NCERT Solutions Class 9 Chapter 1.
5. Why should you wear cotton clothes during summer?
We should wear cotton clothes during summers because cotton is a very good material at absorbing water and exposing the water to the atmosphere where the particles in the liquid evaporate easily and these particles try to regain energy from the near surroundings causing a cooling effect on our bodies. So, the perspiration keeps us cool during summers and the cotton material facilitates the evaporation process even more.