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 and convection conduction and radiation conduction, convection, and radiation conduction None 2. 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 designed for lab purposes such as checking boiling point, freezing point etc. Laboratory thermometers are used to measure body temperature. None 3. Which of the following minimizes the transference of heat in a thermos flask?1. Conduction2. Convection3. Radiation 1,2,and 3 1 and 2 2 and 3 1 and 3 None 4. Among the following what should not be done while or before using a clinical thermometer? Wash the thermometer with hot water. 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. None 5. Two thin blankets are warmer than one blanket of their combined thickness, this happens, because None of the above one blanket is heavier Double layer prevent transmission of heat Two blankets have large mass None 6. 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 plastics have a lower density than metals plastics have a higher thermal conductivity than metals metals have higher thermal capacity than plastics metals are good conductor of heat None 7. The rise in temperature of a substance depends on the quantity of heat supplied the mass of the substance the nature of the substance all the above None 8. 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 The heat of the sun warming our planet A microwave oven cooking a meal None 9. 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 Evaporation None of these None 10. In which of the following processes, convection does not take place primarily? Heating air around a furnace Warming of glass of bulb due to filament Sea and land breeze Boiling of water None 11. Lake water never completely freezes because both of the above Principle of conduction prevents it Principle of convection prevents it none of the above None 12. A laboratory thermometer is dipped in a beaker containing hot water. As the thermometer is removed the mercury level will fall rise neither rise nor fall it may rise or fall depending upon how much water is kept inside the beaker None 13. 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 either Spherical bulb thermometer both equally 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 B A All of the above. None 15. A laboratory thermometer is dipped in a beaker containing ice. As the thermometer is removed the mercury level will rise fall neither rise nor fall either rise or fall depending upon how much ice is kept inside the beaker None 16. 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_______ radiation conduction thermal expansion reflection None 17. 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 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 It allows the level of the mercury to rise when taken out of the mouth None 18. 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. both the above explains correctly all of the above None 19. Choose the correct answer from the alternatives given :For measuring very high temperature, we use Mercury thermometer Platinum resistance thermometer None of the above Thermoelectric pyrometer None 20. An ideal thermometer should have Small heat capacity Large heat capacity Medium heat capacity Variable heat capacity 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.
