Ncert- science – class 7- Chapter 3 – Heat 2 Welcome to your Ncert- science - class 7- Chapter 3 – Heat 2 1. A laboratory thermometer is dipped in a beaker containing hot water. As the thermometer is removed the mercury level will fall neither rise nor fall rise it may rise or fall depending upon how much water is kept inside the beaker None 2. 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_______ thermal expansion conduction reflection radiation None 3. Lake water never completely freezes because both of the above Principle of convection prevents it none of the above Principle of conduction prevents it None 4. Which of the following is not true about Laboratory thermometers ? Laboratory thermometers are used to measure temperatures with a high degree of precision. Range of laboratory thermometer is -10C to 110C Laboratory thermometers are used to measure body temperature. Laboratory thermometers are designed for lab purposes such as checking boiling point, freezing point etc. None 5. 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 and convection conduction, convection, and radiation conduction conduction and radiation None 6. 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? B A C All of the above. None 7. The rise in temperature of a substance depends on the nature of the substance the quantity of heat supplied all the above the mass of the substance None 8. An ideal thermometer should have Variable heat capacity Small heat capacity Medium heat capacity Large heat capacity None 9. 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? Cylindrical bulb thermometer both equally either Spherical bulb thermometer None 10. 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 ? Sublimation Conduction None of these Evaporation None 11. A laboratory thermometer is dipped in a beaker containing ice. As the thermometer is removed the mercury level will neither rise nor fall fall rise either rise or fall depending upon how much ice is kept inside the beaker None 12. 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, A continuous conductive channel is produced between the different layers of water in the pipe which circulates the heat. both the above explains correctly Differences in densities produced between the bottom and the top of water , in turn produce the driving force which continuously circulates the water. all of the above None 13. Two thin blankets are warmer than one blanket of their combined thickness, this happens, because one blanket is heavier Two blankets have large mass None of the above Double layer prevent transmission of heat None 14. 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 Handle the thermometer with care, as you handle any glass articles. Wash the thermometer with hot water. None 15. Identify the statement in which the mode of heat transfer is convection ? Ice cubes cooling a drink The heat from an electric stove warming a frying pan A microwave oven cooking a meal The heat of the sun warming our planet None 16. 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 metals have higher thermal capacity than plastics plastics have a lower density than metals None 17. Choose the correct answer from the alternatives given :For measuring very high temperature, we use Thermoelectric pyrometer Platinum resistance thermometer None of the above Mercury thermometer None 18. What is the use of kink near the bulb in clinical thermometer? It prevents the level of the mercury from falling 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 rising when taken out of the mouth It allows the level of the mercury to fall when taken out of the mouth None 19. In which of the following processes, convection does not take place primarily? Sea and land breeze Boiling of water Heating air around a furnace Warming of glass of bulb due to filament None 20. Which of the following minimizes the transference of heat in a thermos flask?1. Conduction2. Convection3. Radiation 1 and 3 1,2,and 3 2 and 3 1 and 2 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.
