Physics [Heat And Thermodynamics] Questions for Railway ALP Stage-II Exam : 24th November 2018

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Q1. Gas thermometers are more sensitive than the liquid thermometers because the gases.
गैस थर्मामीटर तरल थर्मामीटर की तुलना में अधिक संवेदनशील होते हैं क्योंकि गैसें-
(a) are lighter/ हल्की होती है
(b) have how specific heat/ कम विशिष्ट ऊष्मा होता है
(c) have high specific heat/ उच्च विशिष्ट ऊष्मा होता है
(d) have large coefficient of expansion/ विस्तार का बड़ा गुणांक है
Show Answer
Sol. Gas thermometers are more sensitive than the liquid thermometers because the gas have the large coefficient of expansion. In expansion of gases, there are two coefficients: The volume coefficient (V) and the pressure coefficient (pr).
The change in volume of gas per unit volume per unit degree Celsius at constant of volume expansion. And the change as the pressure coefficient of expansion.

Q2. Centigrade and fahrenheit temperature are the same at
सेल्सियस और फारेनहाइट किस तापमान पर समान होते हैं?
(a) -2730
(b) -400
(c) 320
(d) 400

Show Answer
Sol. To find the temperature when both are equal, we use an old algebra trick and just set ºF = ºC and solve one of the equations. So the temperature when both the Celsius and Fahrenheit scales are the same is -40 degrees.

Q3. Amount of water vapour (gaseous) in a given volume of air (cubic metre) is known as
हवा के आयतन में (घन मीटर) जल वाष्प (गैसीय) की मात्रा को किस रूप में जाना जाता है?
(a) missing ratio/लुप्त अनुपात
(b) relative humidity/ सापेक्षिक आर्द्रता
(c) absolute humidity/ पूर्ण आर्द्रता
(d) specific humidity/ विशिष्ट आर्द्रता

Show Answer
Sol. Amount of water vapour in unit volume of air expressed in grams per cubic metre is retermed to as the absolute humidity.
On the other hand, the relative humidity of air at a given temperature is the ratio o9f mass of water vapour actually present in a certain volume of air to the mass of water vapour required to saturate the same volume of air at the same temperature.

Q4. Lakes freeze in cold countries in winter, leaving the water underneath at
सर्दी में ठंडे देशों में झील जम जाती है, जिससे नीचे पानी का तापमान कितना हो जाता है?
(a) 00C
(b) 00F
(c) 40C
(d) 40F

Show Answer
Sol. Water expands on freezing for the following reason. In liquid water, the particles (water molecules) are close together. But in ice, the molecules link up in a very open structure that actually takes up more space than in the liquid. Ice has lower density than liquid water.
Because of its lower density. Ice floats on water when liquid water is cooled, the molecules start forming into an open structure at 40 C, just before freezing point is reached. As a result, water expand very slightly as it is cooled from 40 C to 00 C.

Q5.The water from a hand pumps is warn in winter because
एक हैण्ड पंप में सर्दी में पानी गर्म होता है क्योंकि
(a) Our body is cold in winter and the water appears to be warm/ हमारा शरीर सर्दियों में ठंडा होता है और पानी गर्म लगता है
(b) the temperature inside the earth is higher than the atmospheric temperature/ पृथ्वी के अंदर का तापमान वायुमंडलीय तापमान से अधिक है
(c) The pumping process causes friction which warms up the water/ पंपिंग प्रक्रिया के कारण घर्षण होता है जो पानी को गर्म करता है
(d) Inside water comes out and absorbs heat from the environment/ पानी बाहर आता है और पर्यावरण से गर्मी सोख लेता है

Show Answer
Sol. The water from a hand pump is warm in winter because the temperature inside the earth is higher than the atmospheric temperature and in the summer season the outside temperature is higher than the water of the pump and therefore, it feels cold.

Q6.What changes will happen to a bowl of ice and water kept at exactly zero degree Celsius?
यदि एक बर्फ के कटोरे और पानी के कटोरे को शून्य डिग्री सेल्सियस पर रखा जाता है तो क्या परिवर्तन होगा?
(a) All ice will melt/सभी बर्फ पिघल जाएगी
(b) All water will become ice/सभी पानी बर्फ बन जाएगा
(c) No change will happen/कोई परिवर्तन नहीं होगा
(d) Only some ice will melt/केवल कुछ बर्फ पिघलेगी

Show Answer
Sol. Zero degree celsius is called the freezing point of water at which the mixture of fresh water and ice has an equilibrium temperature.
When heat is added to the mixture ice starts melting but when heat is removed water starts freezing. Thus, no any change would be observed when the bowl of ice and water is kept at exactly zero degree celsius.

Q7.Heat transfer horizontally within the atmosphere is called
वायुमंडल के भीतर क्षैतिज रूप से हीट ट्रांसफर को क्या कहा जाता है?
(a) conduction/ संचालन
(b) convection/ संवहन
(c) absorption/ अवशोषण
(d) advection/ अभिवहन
Show Answer
Sol. The horizontal transfer of heat by the wind is called the process of advection which is a transport mechanism of the substance. It is the property of a fluid due to its bulk motion. The transport of pollutant or silt in the river by means of bulk water flow downstream is an example of advection.

Q8.What happens to a liquid when the vapour pressure equals the atmospheric pressure?
जब वाष्प दबाव और वायुमंडलीय दबाव बराबर होता है तो तरल का क्या होता है?
(a) The liquid cools/ तरल ठंडा हो जाता है
(b) The liquid boils/ तरल उबल जाता है
(c) No change/ कोई परिवर्तन नहीं होता है
(d) The liquid evaporates/ तरल का वाष्पीकरण हो जाता है
Show Answer
Sol. When the vapour pressure equals the atmospheric pressure, the liquid starts boiling as the vapour pressure being low and since the pressure inside the liquid is equal to atmospheric pressure the bubbles of water vapour cannot boil. At the boiling point, the saturated vapour pressure is equal to the atmospheric pressure and the bubbles form.

Q9.Which one of the following has the highest value of specific heat?
निम्नलिखित में से क्या विशिष्ट ऊष्मा का उच्चतम मूल्य है?
(a) Glass/ग्लास
(b) Copper/कॉपर
(c) Lead/ लेड
(d) Water/पानी
Show Answer
Sol. Water has the highest value of specific heat which is the amount of heat required to raise the temperature of 1g of substance by 10 C. The specific heat of water is 1 cal/ gram0C = 4.2 J/g0C which is higher than any other common substance. Due to having the highest value of specified heat, water plays a very important role in the temperature regulation.

Q10.Pipelines in cold countries often bursts in winter, because
ठंडे देशों में अक्सर सर्दी में पाइपलाइन फट जाती है, क्योंकि
(a) water freezes and expands in its volume/ पानी जम जाता है और यह आयतन में बढ़ जाता है
(b) temperature of ice is less than that of water/ बर्फ का तापमान पानी की तुलना में कम है
(c) pipelines contract in their volume/ पाइपलाइनों का आयतन कम हो जाता है
(d) pipelines expand due to freezing/ ठंड के कारण पाइपलाइनों का विस्तार हो जाता है
Show Answer
Ans. (a)
Sol. Water expand on freezing in liquid water, the particle are close together. But in the ice, the molecules link up in a very open structure. Because of the lower density of ice, it floats on water.
When liquid water is cooled, the molecules start forming into an open structure at 40C just before the freezing point is reached. As a result, water expands very slightly as it is cooled from 40C to O0C. It takes up least space and therefore has its maximum density, at 40C.

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