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