Class 7 Science Chapter 3 MCQ

We are advised not to hold the thermometer bulb while reading it, as the level of mercury increases from the actual reading due to our body temperature.

There are many circumstances where clinical thermometer can break. Here, all the options are correct. Your answer will be option [D].

(36.4 + 37.4 + 36.6) degree Celsius = 110.4 For getting average body tem we should divide: “Total temperature” by “Number of times” Therefore, 110.4/3 = 36.8 degree Celsius

Conduction occurs when two objects at different temperatures are in contact with each other. Heat flows from the warmer to the cooler object until they are both at the same temperature. Conduction is the movement of heat through a substance by the collision of molecules. This process continues until heat energy from the warmer object spreads throughout the cooler object, like the heat from the milk spreading throughout the metal spoon dipped in it. Hence, option [A] is correct.

The air trapped between the layers of newspaper does not allow heat to pass through so it helps the beggar to keep himself warm.

As we know, that gold and silver are the best conductor of heat and electricity whereas tungsten is a poor conductor of heat and electricity. Hence, your answer will be option [D].

Thermo flask is a special kind of flask for keeping liquids. It prevents loss or gain of heat by any of the three methods. It keeps liquid warm or cold for a long time. It was invented by Sir James Dewar in 1893. He was a Scottish chemist and physicist.

Thermometer is a device which is used to measure the degree of coldness or hotness of an object. Rest all are incorrect. Hence, your answer will be option [C].

A land which is surrounded by water heated not by convection. From the sun the heat comes to us by the process of radiation and heated all the objects which is present on the earth. Therefore, a land which is surrounded by water heated by radiation not by convection.

A clinical thermometer consists a uniform glass tube. Rest all the options are correct. Hence, your answer will be option [A].

Since, a marble tile is a good conductor of heat as compared to the wood, therefore a marble tile will allow heat to pass through itself easily, keeping it a cool on a winter morning.

Most of us use the word ‘heat’ to mean something that feels warm, but science defines heat as the flow of energy from a warm object to a cooler object. Heat spontaneously passes to its surroundings with medium or without any medium. Heat energy is the result of the movement of tiny particles called atoms, molecules or ions in solids, liquids and gases.

There is a lot of concern over the use of mercury in thermometers. Mercury is a toxic substance and is very difficult to dispose of if a thermometer break. These days, digital thermometers are available which do not use mercury. Hence, your answer will be option [C].

The temperature 37 degree Celsius is described in Celsius scale while the temperature 98.6 degree Fahrenheit is described in Fahrenheit scale but they are actually equal. Both these values represent the normal average temperature of a human body.

Mercury is the only metal which is found in liquid state at room temperature and it expands when it receives heat. We should avoid keeping the clinical thermometer in the sun or near a flame because the clinical thermometer is designed to measure the temperature of human body only. This thermometer has the range of 35 degree Celsius to 42 degree Celsius. It may break in the sun or near a flame.

We know that wood is non-conductor of heat or cold. It acts as an insulator. So, when wooden spoon is dipped in a cup of ice cream its other end does not become cold. Hence, your answer will be option [D].

There are many conditions to break clinical thermometer as when kept in Sun, when hits by hard objects and when dipped in hot tea. Hence, your answer will be option [D].

Clinical thermometer and digital thermometer are used to measure body temperature and laboratory thermometer is used to measure the temperature of boiling water or any object other than human body.

Heat is a form of energy whereas temperature is a thermal condition of body. Heat is a total amount of internal energy of a body while temperature is proportional to average kinetic energy of a molecules of a body. Rest all the options are correct except option [A].

After gold and silver, copper is a better conductor of heat than the stainless steel. And tungsten is worst conductor of heat which is used in electric bulb filament for its property of resistance. Hence, your answer will be option [C].

The transfer of heat by radiation does not require any medium. It can take place whether a medium is present or not. From the sun the heat comes to us by this process which is known as radiation. When we sit in front of a room heater, we get heat by this process. All the objects are heated from the rays of sun by this process.

We know that Mercury is liquid at room temperature and expand with heat. Expansion may apply pressure to break it.

We are advised not to hold the thermometer bulb while reading it, as the level of mercury increases from the actual reading due to our body temperature. Hence, your answer will be option [D].

We will prefer white fabric tent in case of summer because it reflects all the radiations from the sun and keeps us cool inside the tent.

The mixture will have temperature in between 30 degree Celsius and 50 degree Celsius. They want to come on the same temperature. As one is released his temperature and other one is absorbed the temperature which is released. Therefore, we can say heat absorbed is equal to heat released. As heat is never been destroyed. Since, the hot water (at 50 degree Celsius) will try to lose its heat to the cold water (at 30 degree Celsius).