THERMAL PROPERTIES OF MATTER QUIZ-20
Dear Readers,
JEE Advanced Physics Syllabus can be referred by the IIT aspirants to get a detailed list of all topics that are important in cracking the entrance examination. JEE Advanced syllabus for Physics has been designed in such a way that it offers very practical and application-based learning to further make it easier for students to understand every concept or topic by correlating it with day-to-day experiences. In comparison to the other two subjects, the syllabus of JEE Advanced for physics is developed in such a way so as to test the deep understanding and application of concepts.
Q191. Statement 1: The absorbance of a perfect black body is unity
Statement 2: A perfect black body when heated emits radiations of all possible wavelengths at that temperatures
Solution
191(b) Both assertion and reason are true but reason is not correctly explaining the assertion
191(b) Both assertion and reason are true but reason is not correctly explaining the assertion
Q192. Statement 1: The temperature at which Centigrade and Fahrenheit thermometers read the same is -40o
Statement 2: There is no relation between Fahrenheit and Centigrade temperature
Solution
192(c) The relation between F and C scale is, C/5=(F-32)/9. If F=C⇒C=-40℃,i.e., at -40^o the Centigrade and Fahrenheit thermometers reads the same
192(c) The relation between F and C scale is, C/5=(F-32)/9. If F=C⇒C=-40℃,i.e., at -40^o the Centigrade and Fahrenheit thermometers reads the same
Q193. Statement 1: The molecules at 0℃ ice and 0℃ water will have same potential energy
Statement 2: Potential energy depends only on temperature of the system
Solution
193(d) The potential energy of water molecules is more. The heat given to melt the ice at 0℃ is used up in increasing the potential energy of water molecules formed at 0℃
193(d) The potential energy of water molecules is more. The heat given to melt the ice at 0℃ is used up in increasing the potential energy of water molecules formed at 0℃
Q194. Statement 1: A man would feel iron or wooden balls equally hot at 98.4°F
Statement 2: At 98.4°F both iron and wood have same thermal conductivity
Solution
194 (c) The 98.4℉ is the standard body temperature of a man. If a man touches an iron or wooden ball at 98.4℉, no heat transfer takes place between ball and man, so both the balls would feel equally hot for the man
194 (c) The 98.4℉ is the standard body temperature of a man. If a man touches an iron or wooden ball at 98.4℉, no heat transfer takes place between ball and man, so both the balls would feel equally hot for the man
Q195. Statement 1: A common model of a solid assumes the atoms to be point executing SHM about mean lattice positions. This model cannot explain thermal expansion of solids
Statement 2: The average distance over a time period of oscillation between the particles remains constant
Solution
195 (a) The correct model is one in which the atoms fling away from the equilibrium position through a greater distance than the one by which they come closer
195 (a) The correct model is one in which the atoms fling away from the equilibrium position through a greater distance than the one by which they come closer
Q196. Statement 1: If the temperature of a star is doubled then the rate of loss of heat from it becomes 16 times
Statement 2: Specific heat varies with temperature
Solution
196 (b) This is in accordance with the Stefan’s law E∝T^4
196 (b) This is in accordance with the Stefan’s law E∝T^4
Q197. Statement 1: Perspiration from human body helps in cooling the body
Statement 2: A thin layer of water on the skin enhances its emissivity
Solution
197 (c) When water leaves the body through perspiration energy content of molecules remained in body decreases, therefore temperature also decreases
197 (c) When water leaves the body through perspiration energy content of molecules remained in body decreases, therefore temperature also decreases
Q198. Statement 1: Two stars S_1 and S_2 radiate maximum energy at 360 nm and 480 nm, respectively. Ratio of their absolute temperatures is 4:3
Statement 2: According to Wien’s law λT=b (constant)
Solution
198(a) On comparison T_1/T_2 =λ_2/λ_1 =480/360=4/3
198(a) On comparison T_1/T_2 =λ_2/λ_1 =480/360=4/3
Q199. Statement 1: While measuring the thermal conductivity of liquid experimentally, the upper layer is kept hot and the lower layer is kept cold
Statement 2: This avoids hearting of liquid by convection
Solution
199 (a) We know that to measure thermal conductivity of liquids experimentally, they must be heated from the top i.e., upper layer is kept hot and lower layer is kept cold, so as to prevent convection in liquids
199 (a) We know that to measure thermal conductivity of liquids experimentally, they must be heated from the top i.e., upper layer is kept hot and lower layer is kept cold, so as to prevent convection in liquids
Q200. Statement 1: Specific heat capacity is the cause of formation of land and sea breeze
Statement 2: The specific heat of water is more than land
Solution
200 (a) The temperature of land rises rapidly as compared to sea because of specific heat of land is five times less than that of sea water. Thus, the air above the land becomes hot and light so rises up so pressure drops over land. To compensate the drop of pressure, the cooler air from sea starts blowing towards lands, setting up sea breeze. During night land as well sea radiate heat energy. The temperature of land falls more rapidly as compared to sea water, as sea water consists of higher specific heat capacity. The air above sea water being warm and light rises up and to take its place the cold air from land starts blowing towards sea and set up breeze >
200 (a) The temperature of land rises rapidly as compared to sea because of specific heat of land is five times less than that of sea water. Thus, the air above the land becomes hot and light so rises up so pressure drops over land. To compensate the drop of pressure, the cooler air from sea starts blowing towards lands, setting up sea breeze. During night land as well sea radiate heat energy. The temperature of land falls more rapidly as compared to sea water, as sea water consists of higher specific heat capacity. The air above sea water being warm and light rises up and to take its place the cold air from land starts blowing towards sea and set up breeze >
