Ncert- science – class 7- Chapter 3 – Heat 2 Welcome to your Ncert- science - class 7- Chapter 3 – Heat 2 1. A red hot brick is placed on an iron tripod stand which stands on a large block of copper. The brick loses heat by: conduction conduction and radiation conduction, convection, and radiation conduction and convection None 2. Among the following what should not be done while or before using a clinical thermometer? Don't hold the thermometer by the bulb while reading it. Ensure that before use the mercury level is below 35 degree C Wash the thermometer with hot water. Handle the thermometer with care, as you handle any glass articles. None 3. Suppose a liquid in a container is heated at the top rather than at the bottom. What is the main process by which the rest of the liquid becomes hot ? Evaporation Conduction None of these Sublimation None 4. An ideal thermometer should have Large heat capacity Variable heat capacity Small heat capacity Medium heat capacity None 5. Choose the correct answer from the alternatives given :For measuring very high temperature, we use None of the above Platinum resistance thermometer Thermoelectric pyrometer Mercury thermometer None 6. Two thermometers are constructed in the same way except that one has a spherical bulb and the other a cylindrical bulb; which one will respond quickly to temperature changes? both equally either Spherical bulb thermometer Cylindrical bulb thermometer None 7. A long silver tea spoon is placed in a cup filled with hot tea. After some time, the exposed end (the end which is not dipped in tea) of the spoon becomes hot even without a direct contact with the tea. This phenomenon can be explained mainly by_______ reflection thermal expansion conduction radiation None 8. Identify the statement in which the mode of heat transfer is convection ? The heat of the sun warming our planet A microwave oven cooking a meal The heat from an electric stove warming a frying pan Ice cubes cooling a drink None 9. Which of the following is not true about Laboratory thermometers ? Laboratory thermometers are used to measure temperatures with a high degree of precision. Laboratory thermometers are used to measure body temperature. Laboratory thermometers are designed for lab purposes such as checking boiling point, freezing point etc. Range of laboratory thermometer is -10C to 110C None 10. On a cold day when a room temperature is 15 degree C, the metallic cap of a pen becomes much colder than its plastic body, though both are at the same temperature of 15 degree C, because metals are good conductor of heat plastics have a higher thermal conductivity than metals plastics have a lower density than metals metals have higher thermal capacity than plastics None 11. A laboratory thermometer is dipped in a beaker containing hot water. As the thermometer is removed the mercury level will rise fall it may rise or fall depending upon how much water is kept inside the beaker neither rise nor fall None 12. Lake water never completely freezes because Principle of convection prevents it Principle of conduction prevents it both of the above none of the above None 13. In experiment of heat transfer by convection, water inside the pipe completely gets heated (with the application of heat source). This can be explained best by which of the following statements, Differences in densities produced between the bottom and the top of water , in turn produce the driving force which continuously circulates the water. A continuous conductive channel is produced between the different layers of water in the pipe which circulates the heat. all of the above both the above explains correctly None 14. Beaker A contains hot water. Beaker B contains cold water. Beaker C contains a mixture of hot and cold water. If initially your hand is put into a beaker containing ice, then putting your hand in which of the beakers A, B or C will give a sensation of warmth? C A B All of the above. None 15. In which of the following processes, convection does not take place primarily? Boiling of water Warming of glass of bulb due to filament Sea and land breeze Heating air around a furnace None 16. The rise in temperature of a substance depends on the nature of the substance the quantity of heat supplied the mass of the substance all the above None 17. Two thin blankets are warmer than one blanket of their combined thickness, this happens, because Double layer prevent transmission of heat Two blankets have large mass None of the above one blanket is heavier None 18. A laboratory thermometer is dipped in a beaker containing ice. As the thermometer is removed the mercury level will fall neither rise nor fall either rise or fall depending upon how much ice is kept inside the beaker rise None 19. Which of the following minimizes the transference of heat in a thermos flask?1. Conduction2. Convection3. Radiation 1 and 2 1 and 3 2 and 3 1,2,and 3 None 20. What is the use of kink near the bulb in clinical thermometer? It prevents the level of the mercury from rising when taken out of the mouth It allows the level of the mercury to rise when taken out of the mouth It prevents the level of the mercury from falling when taken out of the mouth It allows the level of the mercury to fall when taken out of the mouth None Time's up Please Share This Share this content Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Leave a Reply Cancel replyCommentEnter your name or username to commentEnter your email address to commentEnter your website URL (optional) Save my name, email, and website in this browser for the next time I comment.
