# NCERT Exemplar Solutions Class 9 Science Solutions for Matter in our Surroundings - Exercise in Chapter 1 - Matter in our Surroundings

Question 2 Matter in our Surroundings - Exercise

Seema visited a Natural Gas Compressing Unit and found that the gas can be liquefied under specific conditions of temperature and pressure. While sharing her experience with friends she got confused. Help her to identify the correct set of conditions

(a) Low temperature, low pressure

(b) High temperature, low pressure

(c) Low temperature, high pressure

(d) High temperature, high pressure

The answer is c) Low temperature, high pressure

Explanation:

To compress gas into a liquid, low temperature and high pressure are required. Between the particles of gas, there is a lot of space. On applying pressure, particles get closer and they start attracting each other to form a liquid. A lot of heat is generated when gas is compressed hence it is necessary to cool it. Cooling lowers the temperature of compressed gas and helps in liquefying it.

Video transcript
"hello students welcome to leader homework i am akruti and i teach science at leader learning and today we will discuss the question which says seyma visited natural gas compressing unit and found out that gas can be liquefied under specific conditions of temperature and pressure by sharing her experience with friends she got confused help her to identify the correct set of conditions now the four set of conditions is given to us and we need to tell which one is the correct set of temperature and pressure helpful for compressing or for liquefying the gas now the explanation would be to compress the gas into liquid low temperature and high pressure are needed low temperature and high pressure are the favorable conditions therefore the right option would be answer c let's see why because between the particles of gas we know there is a lot of space particles of gas are very far from each other and there is a lot of space now on applying pressure if we apply let's say it's it's in a closed vessel and we are applying pressure on it so these particles will come closer and when they will come closer they will start attracting to each other and once they start once they start attracting to each other so they try to come closer to each other try to convert themselves into the liquid state and while they are doing that a lot of heat is released now when while this is doing it is happening a lot of heat is released hence it is really necessary to cool to cool this gas therefore cooling lowers the temperature of the compressed gas and hence it is helpful in liquefying the gas so from gas we are converting it into liquid form with the help of high pressure high pressure brings them closer and since a lot of heat is released to overcome that therefore it is necessary to keep the temperature of the compressed gas very low so the right options would be low temperature and high pressure option c is the answer if you like the explanation please put a thumbs up if you have any query you can ask in the comment section and for more such video solutions please subscribe to leader channel keep learning bye"
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