Ncert- science – class 7- Chapter 3 – Heat 1 Welcome to your Ncert- science - class 7- Chapter 3 – Heat 1 1. Two thermometers are used to record the temperature of a room and the bulb of one is wrapped in a wet hanky. None of the above The temperature recorded by the wet-bulb thermometer will be greater than that recorded by the other The temperature recorded by dry-bulb thermometer will be greater than that recorded by the other The temperature recorded by both will be same None 2. The layers of the atmosphere are heated through Convection Conduction (b) and (c) both Radiation None 3. Glass cracks when heated; while a metal does not because None of these Glass is bright Glass is a bad-conductor Glass has pores inside None 4. Woollen clothes are used in winter season because woollen clothes Provide heat to body continuously Are good sources for producing heat Absorb heat from surroundings Are bad conductors of heat None 5. Weather reports are made using __________ thermometer Laboratary None of these Clinical Maximum-minimum None 6. Thermal insulation is used to reduce the flow of heat stop the flow of heat absorb heat reverse the heat flow direction None 7. Snow is more heat-insulating than ice, because Air is filled in porous of snow Ice is more bad conductor than snow Air is filled in porous of ice Density of ice is more None 8. Mercury is often used in clinical thermometers. Which one of the following properties of mercury is not a reason for this ? It is a liquid at room temperature It has high density. It is shiny The coefficient of the thermal expansion is large None 9. The standard fixed point for temperature measurement is used these days is : that temperature at which pure ice and pure water coexist that temperature at which ice, water and water vapour coexist none of the above melting point of ice at S.T.P. None 10. In which of the following process convection does not take place primarily? Sea and land breeze Warming of glass of bulb due to filament Boiling of water Trade wind None 11. Choose the correct alternative:In the process of convection, heat travels downwards upwards sideways in all direction None 12. Which of these we could identify as cold with our sense of touch? Ice A glass of water Hot tea Cup of hot coffee None 13. The velocity of heat radiation in vacuum is Equal to that of sound Less than that of light Equal to that of light Greater than that of light None 14. A metal spoon is placed in one of two identical cups of hot coffee. Why does the cup with the spoon have a lower temperature after a few minutes ? None of these Energy is removed from the coffee mostly by conduction through the spoon. Energy is removed from the coffee mostly' by convection through the spoon. Energy is removed from the coffee mostly by radiation through the spoon. None 15. Two thermometers are constructed in such a way that one has a spherical bulb and the other has elongated cylindrical bulb. The bulbs are made of same material and thickness. Then : none of both bulbs respond to temperature changes spherical bulb will respond more quickly to temperature changes both bulbs will respond same to temperature changes cylindrical bulb will respond more quickly to temperature changes. None 16. Why is sense of touch not reliable? None of these It doesn't tell us what is hot or cold It doesn't work for all of us It might misguide us None 17. If the temperature of a hot body is increased by 50% then the increase in the quantity of emitted heat radiation will be 200% 400% 125% 300% None 18. A beggar wrapped himself with a few layers of newspaper on a cold winter night. This helped him to keep himself warm because Newspaper is a conductor of heat. Air trapped between the layers of newspaper is a bad conductor of heat. Friction between the layers of newspaper produces heat. Newspaper is at a higher temperature than the temperature of the surrounding. None 19. Mark correct option or options : Insect temperature is measured by thermocouple thermometer Sun temperature is measured by radiation pyrometer Both Sun temperature is measured by radiation pyrometer and Insect temperature is measured by thermocouple thermometer Moon's temperature is measured by thermometer None 20. A thermos flask is polished well To reflect all radiations from outside To make attractive To absorb all radiations from outside For shining 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.
