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