1). What is the average kinetic energy of the molecules contained in a body?
i. heat
ii. temperature
iii. thermal energy
iv. internal energy
Ans: ii. temperature
2).Which of the following is equivalent to 1 calorie heat?
i. 1.2 J
ii. 2.2J
iii. 3.2 j
iv 4.2J
Ans: iv. 4.2 J
3).Which of the following is the SI unit of temperature?
i.kelvin
ii. degree celsius
iii. fahrenheit
iv. joule
Ans: i.kelvin
4). Which type of thermometer has thermistor at its ends?
i. clinical thermometer
ii. infrared thermometer
iii. liquid thermometer
iv. digital thermometer
Ans: iv. digital thermometer
5). What is the range of temperature on the scale of a simple thermometer?
i. 10 °C to 100 °C
ii. -10 °F to 100 °F
iii. -10 °C to 100 °C
iv. 10 °F to 100 °F
Ans: i. 10 °C to 100 °C
6). Which of the following sets are freezing and boiling points of alcohol?
i. -39 °C and 78 °C
ii.-117 °C and 78 °C
iii. -39 °C and 457 °C
iv. -117 °C and 457 °C
Ans: iii. -117 °C and 78 °C
7). When does land breeze occur?
i. day
ii. night
iii. morning
iv. evening
Ans: ii. night
8). Which of the following is the specific heat capacity of mercury?
i. 240 J/kg °C
ii. 140 J/kg °C
iii. 340 J/kg °C
iv. 410 J/kg °C
Ans: ii. 140 J/kg °C
9). Which of the following is the specific heat capacity of water?
i. 4200 J/kg °C
ii. 4100 J/kg °C
iii. 2100 J/kg °C
iv. 2200 J/kg °C
Ans: i. 4200 J/kg °C
10). Distinguish between:
a. Heat and temperature
| Heat | temperature |
| Heat is like the energy that moves from a hot thing to a colder thing. It’s the reason why things get warmer when they’re near something hot. | Temperature is how we measure how hot or cold something is. It’s like a scale that helps us compare how hot one thing is compared to another. |
| Imagine heat is like a hot potato being passed from one person to another | Temperature is like saying how hot or cool the potato is at a given moment |
| Heat can make things change – like melt ice or make water boil. | Temperature helps us describe how hot or cold things are without changing them. |
C. Heat and thermal energy
| Heat | thermal energy |
| It’s the transfer of energy from a warmer object to a cooler object. | Thermal energy is the total energy stored in an object due to the movement of its particles. |
| Heat is about the transfer of thermal energy from one thing to another | Thermal energy is the whole amount of energy stored in an object, whether it’s transferring or not. |
| Heat is what causes things to warm up, change state (like melting), or cool down. | Thermal energy tells us how much warmth or hotness a substance possesses overall. |
b. Simple thermometer and clinical thermometer
| Simple thermometer | clinical thermometer |
| A simple thermometer is basic and used for general temperature measurements, like checking the weather or room temperature. | A clinical thermometer is designed specifically to measure the human body temperature and is used to check if someone has a fever or is sick. |
| A simple thermometer usually has a wider temperature range and can measure a broader spectrum of temperatures. | A clinical thermometer has a narrow temperature range, focusing on the typical human body temperature range. |
| A simple thermometer can be made of various materials and is often less fragile, suitable for general use. | A clinical thermometer is typically made of high-quality materials, ensuring accuracy and durability for regular use in a medical setting. |
d. Lower fixed point and upper fixed point
| Lower fixed point | upper fixed point |
| The lower fixed point is a standard temperature used as a reference for measuring temperature. | The upper fixed point is another standard temperature used as a reference for measuring temperature. |
| It’s a specific temperature point used to calibrate thermometers and temperature measuring devices. | It’s a specific temperature point used for calibration and comparison, just like the lower fixed point. |
| An example is the freezing point of water, often used as the lower fixed point in the Celsius scale. | An example is the boiling point of water, often used as the upper fixed point in the Celsius scale. |
11). Define heat.
Ans:Heat is a kind of energy that makes things warmer. It’s what we feel when we touch something hot, like a warm cup of tea.
12). On what factor does heat depend?
Ans: Heat depends on:
Amount of Stuff (Molecules)
Speed of Movement
Types of Molecules
13). What is the relation of heat with its factors?
Ans: Heat is related to its factors in this way:
More Stuff, More Heat: If you have more things (molecules) in an object, there’s more heat. It’s like having more people in a room, generating more warmth.
Faster Movement, More Heat: When the molecules move quickly, they produce more heat. It’s similar to how running makes you warmer than walking.
Material Matters: Different materials can hold different amounts of heat. Some materials can keep more heat than others.
14). Give the concept of heat on the basis of its molecular motion.
Ans: Heat is like the dance of tiny building blocks (molecules) inside an object. The faster and livelier they dance, the warmer the object becomes. When we add more dancers (more molecules) or make them dance faster, we get more heat, making things hot and cozy.
15). Give the concept of temperature on the basis of its molecular motion.
Ans: Temperature is the speed of the tiny dancers (molecules) at the molecular dance party. If they’re dancing fast, it’s a high temperature (hot); if they’re slow, it’s a low temperature (cool). So, temperature is like the dance energy of the molecules.
16). Define specific heat capacity.
Ans: Specific heat capacity is the amount of energy needed to make a substance warm up or cool down a little bit
17). What is one calorie heat?
Ans: One calorie of heat is a small unit that measures how much warmth or energy is needed to raise the temperature of one gram of water by one degree Celsius.
18). What is anomalous expansion of water?
Ans: Anomalous expansion of water means it expands as it cools down, unlike most substances which contract when they cool. This unique behavior happens in a specific temperature range, making water different from other materials.
19). The specific heat capacity of water is 4200 Jkg-1 °C. What does it mean?
Ans: Specific heat capacity of water (4200 J/kg°C) means that it takes 4200 joules of energy to raise the temperature of 1 kilogram of water by 1 degree Celsius.
20).Define thermometric liquid.
Ans:Thermometric liquid is a substance used in thermometers to measure temperature. It expands or contracts with temperature changes, allowing the thermometer to show the temperature accurately.
21).Describe the structure of a digital thermometer with a diagram.
Ans: A digital thermometer is a device that measures temperature and displays the results on a screen. It has a simple structure and works using a few key components
Temperature Sensor: This is the part of the thermometer that measures the temperature. It could be a thermistor or a semiconductor device.
Microcontroller: This is like the brain of the thermometer. It processes the temperature data from the sensor and performs calculations to convert it into a readable temperature value.
Display: The temperature readings are shown on a digital screen. It could be an LCD (Liquid Crystal Display) or LED (Light Emitting Diode) display.
Battery or Power Source: The thermometer needs power to work, so it has a battery or needs to be connected to a power source.
Buttons: Some thermometers have buttons to allow users to switch between different modes, change the temperature scale (e.g., Celsius or Fahrenheit), or set alarms.
22). Explain the structure of a clinical thermometer.
Ans: A clinical thermometer is a special thermometer for checking how hot or cold a person’s body is. Here’s a simple explanation of its parts:
Heat Sensor: This part feels how hot or cold your body is. It’s like a tiny temperature checker inside the thermometer.
Temperature Scale: Outside, there are numbers showing how hot your body is. You can see this to know your temperature.
Liquid: Inside the thermometer, there is a special liquid. This liquid goes up or down to show your temperature on the scale.
Glass Tube: The liquid is kept in a thin glass tube. It helps keep the liquid inside and allows it to move as the temperature changes.
Tip or Bulb: One end of the thermometer has a tip or bulb. This is where you place it in your mouth or under your arm to measure your body’s heat.
Safe Material: The whole thermometer is made from safe materials like glass or sometimes plastic. This ensures it’s safe to use in your mouth or under your arm.
When you use a clinical thermometer, the heat sensor senses your body’s heat, and the liquid inside moves to show your temperature on the scale. It’s an easy and safe way to check if you have a fever.
23). Describe specific heat capacity in short.
Ans: Specific heat capacity is like a superhero power of a substance. It tells us how much heat energy it needs to get warmer or cooler. Some substances need a lot of heat to change temperature, like a superhero with strong armor, while others need less, like a superhero with a light shield. It’s a measure of how resistant a substance is to changing its temperature when you give it heat or take heat away.
24). What is anomalous expansion of water? Describe the importance of this property of water.
Ans: Water dosen’t obey the normal expansion when it is heated from 0 to 4 degree clesius, it volume first decreases, density becomes maximum at 4 degree celcius then on further heating, it form increase. this is anomalous expansion of water.
Ice Floating: When water freezes into ice, it expands and becomes less dense, making it float. This is crucial for aquatic life as it creates a protective layer on top of water bodies.
Life Survival: If ice sank, it would freeze from the bottom up, making it hard for aquatic life to survive in cold regions.
Climate Balance: The floating ice affects Earth’s climate and helps in maintaining a balanced environment for all living things.
25). Explain the advantages of more specific heat capacity of water in short.
Ans: Water’s high specific heat capacity means it can absorb and hold more heat compared to other substances. This is super helpful because:
Temperature Regulation: It helps keep our bodies and the Earth’s climate at a steady and comfortable temperature.
Cooling Effect: Water can absorb a lot of heat before getting hot, making it great for cooling things down.
Weather Influence: Oceans and lakes, with their high specific heat, help balance temperatures, affecting our weather in a positive way.
Life Support: Water’s ability to hold heat sustains life in aquatic habitats, keeping creatures warm in colder areas.
In simple words, water’s special heat-holding ability helps us stay comfortable, keeps the planet’s weather stable, and supports life in oceans and lakes.
26). How can you determine the lower fixed point in a newly constructed thermometer? Describe with a suitable diagram.
Ans: Determining the lower fixed point in a thermometer is like finding the starting point for measuring temperature. Here’s a simple explanation:
Cooling in Ice: First, put the thermometer in a mixture of crushed ice and water. Ice melts at a specific temperature, and it’s a consistent point, so it’s a good reference.
Wait and Observe: Let the thermometer sit in the ice mixture until the temperature stabilizes. This is when the thermometer and the ice-water mixture are in thermal balance.
Mark the Point: At this stable point, mark the level where the mercury or liquid inside the thermometer settles. This is your lower fixed point.
27). How can you determine the upper fixed point in a newly constructed thermometer? Describe with a suitable diagram.
Ans: Determining the upper fixed point in a thermometer helps establish the highest temperature reference. Here’s a simple way to do it:
Boiling Water: Place the thermometer in boiling water. Boiling water reaches a consistent temperature at a certain point.
Wait and Observe: Allow the thermometer to sit in the boiling water until the temperature stabilizes. This is when the thermometer and the boiling water are in thermal balance.
Mark the Point: At this stable point, mark the level where the mercury or liquid inside the thermometer settles. This is your upper fixed point.
28). What are similarities and dissimilarities between heat and temperature?
Ans: Similarities between heat and temperature:
Both Related to Energy: Both heat and temperature are related to energy. Heat is a form of energy transfer, while temperature is a measure of the average kinetic energy of particles in a substance.
Affect Matter: Both heat and temperature can affect the state or phase of matter (e.g., solid, liquid, gas). Adding heat or increasing temperature can change a substance’s state.
Measured in Degrees: Both heat and temperature are measured in degrees, typically using the Celsius or Fahrenheit scales.
dissimilarities between heat and temperature:
Definition: Heat is the transfer of energy from a warmer object to a cooler one. Temperature, on the other hand, is a measure of how hot or cold an object is, related to the average kinetic energy of its particles.
Nature: Heat is a form of energy, while temperature is a scalar quantity that measures the thermal condition of a substance.
Units: Heat is measured in units of energy (e.g., joules or calories), while temperature is measured in degrees (e.g., Celsius or Fahrenheit).
29).How does a radiation thermometer work? Describe in short.
Ans: A radiation thermometer, often called an infrared thermometer, works like a magic flashlight. Instead of light, it uses infrared rays (a type of heat energy) to measure temperature.
Detecting Infrared Rays: When you point the thermometer at an object, it detects the infrared rays coming from the object. These rays carry the object’s heat.
Converting Rays to Temperature: The thermometer has a special sensor that turns the detected infrared rays into a temperature reading. It’s like reading the heat the object is giving off.
Displaying Temperature: The thermometer shows the temperature on a screen. You can see the temperature without touching the object, which is super useful.
30).Water is used to cool hot engines of vehicles.
Ans: Water is great at absorbing heat. When an engine runs, it gets really hot. Water cools it down by soaking up this heat, making sure the engine doesn’t get too hot and cause damage. It’s like giving the engine a refreshing drink to keep it working well.
31). During a high fever, a piece of wet cloth is kept on the forehead of the patient.
Ans:During a high fever, a wet cloth on the forehead helps cool the body. Evaporation of water from the cloth absorbs some heat, providing relief and lowering the body temperature. It’s like giving the body a cooling hug to reduce the fever’s discomfort.
32).When a beaker filled with water at 4 °C is cooled or heated, the water overflows from the beaker.
Ans: When water at 4°C is heated or cooled, it expands or contracts. This change in volume makes the water level rise or fall, causing it to overflow from the beaker. It’s like the water is trying to find more space or fitting into a smaller one.
33). Mercury is heated faster than water.
Ans: Mercury heats up quickly because its particles move fast and are close together, allowing rapid energy transfer when heated. In contrast, water’s particles move slower and are farther apart, making it heat up more slowly.
34).Clinical thermometer has a constriction above the bulb.
Ans:A clinical thermometer has a narrow part above the bulb called a constriction. This helps in trapping the maximum temperature reached, allowing the thermometer to be read easily after use. It’s like a special design that helps show the highest temperature accurately.
35).When we get out of bed on a very cold morning, we feel the air of the room cold. But when we come back staying out for some time, we feel the air of the same room warmer.
Ans: When we first get out of bed on a cold morning, our body is warm, and the air feels colder in comparison. After being outside for a while, our body temperature drops, and when we return to the room, the air now feels warmer as our perception has adjusted.
36). Water is used in hot water bags.
Ans: Water is used in hot water bags because it can retain and conduct heat well. When heated, water in the bag stores the heat and slowly releases it, providing warmth and comfort.
37).Digital thermometer is more advanced than a mercury thermometer.
Ans: A digital thermometer is more advanced than a mercury thermometer because it gives a quick and precise temperature reading on a screen. It’s easy to use, safe (no mercury), and can store past readings for reference.
38).The temperature of boiling water cannot be measured by using an alcohol thermometer.
Ans:An alcohol thermometer cannot measure the temperature of boiling water accurately because alcohol boils at a lower temperature than water.
39). Days are very hot and nights are very cold in deserts.
Ans: In deserts, days are scorching because of strong sunlight. At night, the lack of clouds lets heat escape quickly, causing it to become very cold. It’s like a natural hot-and-cold cycle in the desert.
40).The water of a well is felt to be warmer early in the morning but colder at day.
Ans: In the morning, the sun hasn’t heated the well water, so it feels warmer compared to the cooler air. As the day progresses, the sun warms the surroundings, making the water feel colder when touched.
41). We wear warm clothes in winter.
Ans: We wear warm clothes in winter to keep our bodies cozy. Warm clothes trap air close to our skin, preventing heat loss and helping us stay comfortable in the cold.
42). Water stored in an earthen pot is colder than the water stored in metallic containers in summer.
Ans: Water stored in an earthen pot is colder than in metallic containers in summer because earthen pots allow water to evaporate through tiny pores. This evaporation cools down the water, making it feel colder.
43). The bulb of a thermometer is made of thin wall but stem is thick walled.
Ans: The bulb of the thermometer is made thin-walled to quickly sense temperature changes in the surrounding environment. The thick-walled stem helps to transmit the temperature accurately from the bulb to the scale without losing heat.
44). Water freezes from upper to lower region in a vessel but ghee and honey solidify from lower to upper region.
Ans: Water freezes from the top down because the top surface loses heat to the colder air. Ghee and honey, being denser, lose heat at the bottom first, causing solidification to start from the bottom and move upward.
45).We sweat in summer.
Ans: We sweat in summer to cool down our bodies. Sweating is like the body’s natural air conditioner—it releases moisture (sweat) on the skin, and when it evaporates, it takes away excess heat, making us feel cooler.
46). Water cannot be used as a thermometric liquid.
Ans: Water cannot be used as a thermometric liquid because it boils and turns into vapor at a lower temperature compared to other suitable liquids like mercury. This limits its use in measuring high temperatures accurately.
