Q1. 1 calorie is 4.81 joules.
1 calorie is 4.81 joules- Wrong
Updated on: 2026-03-31 | Author: Rahul Patil
1 calorie is 4.81 joules- Wrong
1 kg of dry air at a temperature of 40 °C can hold a maximum of 49 g of water vapour- Right
Hope’s apparatus is used to study the anomalous behaviour of water.
4180 joule heat is necessary to raise 1 kg of water from 14.5 °C to 15.5 °C.
All metals have the same specific heat capacity- Wrong
Calorimeters are used to measure specific heat capacity- Right
Calorimeters are used to study anomalous behaviour of water- Wrong
The amount of heat (Q) required to change the temperature of a substance is directly proportional to:
a. the mass of the substance (m).
b. change in temperature of the substance (ΔT).
where ‘c’ is specific heat or specific heat capacity of a substance. From equation (1),
c = `"Q"/("m" Delta "T")` ....(2)
SI unit:
As SI unit of heat is J, mass is kg and change in temperature is °C, SI unit of specific heat capacity is J/kg °C
C.G.S. unit:
As CGS unit of heat is calorie, mass is g and change in temperature is °C, CGS unit of specific heat capacity is cal/g °C
The temperature at which the equilibrium vapour pressure of a liquid becomes equal to the atmospheric pressure is called the boiling point of that liquid.
When temperature of air at early hours in winter falls, air becomes saturated with vapour.
As a result, the excess vapour condenses on surface of objects in the form of dew.
When the dew settles on a glass of vehicles, drops of water accumulating on glass can be seen.
During reheating, ice is converted to water at a temperature of 0 °C- Right
In the given graph, line AB represents conversion of ice into water at constant temperature. When ice is heated, it melts at 0oC and converts into water maintaining constant temperature of 0oC. This constant temperature, at which the ice converts into water is called the melting point of ice.
Also, during this transition, the ice absorbs heat energy. This heat energy is utilised for weakening the bonds between the atoms or molecules in the ice to transform itself into liquid. This heat energy absorbed by ice, at constant temperature, to convert it into liquid is called the latent heat of fusion.
Once all the ice is transformed into water, the temperature of water starts rising. It increases upto 100oC. Line BC in the graph represents rise in temperature of water from 0oC to 100oC.
Thereafter, even though heat energy is supplied to water, its temperature does not rise. The heat energy is absorbed by water at this temperature and is used to break the bonds between molecules of the liquid and convert the liquid into gaseous state. Thus, during transformation from liquid phase to gas phase, heat energy is absorbed by the liquid, but its temperature does not change.
The constant temperature at which the liquid transforms into gaseous state is called the boiling point of the liquid. The heat energy absorbed at constant temperature during transformation of liquid into gas is called the latent heat of vaporization.
The solid object whose specific heat is to be determined is heated and then put in water in a calorimeter.
Solid object loses heat energy to water and calorimeter till temperature of all three become equal.
According to principle of heat exchange,
This means,
mass of the solid object × its specific heat × in its temperature
= (mass of the calorimeter × its specific heat × increase in its temperature) + (mass of the water × its specific heat × increase in its temperature).
Using this equation, if the specific heat of water and calorimeter are known and other physical quantities are measured accurately, the specific heat of solid object can be determined.
The bottle taken out from the refrigerator has a lower temperature than the temperature of the surrounding environment, i.e., outside air in the atmosphere. It cools the air surrounding it. Air in the vicinity becomes saturated with vapour and the excess vapour condenses on the surface of the bottle in the form of water droplets.
This phenomenon takes place due to air reaching its dew point temperature.
Normally, liquids expand on heating and contract on cooling. But water exhibits an exceptional behaviour in the temperature range of 0 °C to 4 °C.
When water is cooled from 4°C to 0°C, it expands instead of contracting. Its volume increases, and its density decreases. At 4°C, the volume of water is at its minimum, and its density is at its maximum.
When the temperature drops below 0°C and water freezes into ice, it expands significantly.
This behaviour of water between temperature intervals of 0 °C to 4 °C is called anomalous behaviour of water.
In cold regions during winter, when water in the cracks of rocks freezes, it expands. This expansion creates pressure on the surrounding rock.
As a result, the rocks experience force from the expanding ice and may crack.
To find: Heat energy (Q)
Calculation: According to principle of heat exchange,
Heat energy needed to raise temperature of piece of iron is 1100 cal.
To find: Heat energy (Q)
Calculation: According to principle of heat exchange,
Heat energy needed to raise temperature of the silver container is 56 cal.
cal/g
Explanation-
cal/g is a unit of specific latent heat while others are units of specific heat.
Newton
Explanation-
Newton is a unit of force while others are units of heat energy.
Earthquake
Explanation-
Others are due to the different phenomenon of light whereas earthquake is a natural disaster.
From the options given below the specific heat of iron is maximum.
If the relative humidity of surrounding air is high then, a prominent white trail will be formed. Also, it will take a longer time for the trail to disappear.
If the relative humidity of surrounding air is low then, a small-sized white trail formed would be formed or it may not get formed at all.
If the relative humidity of air is more than 60%, air is said to be humid and if relative humidity of air is less than 60%, air is said to be dry.
When water vapour condenses around microscopic solid particles such as dust, fog is formed.
To find: Heat energy (Q)
Calculation:
According to the principle of heat exchange,
Heat energy necessary to raise the temperature of the water is 400 kcal.
all of the above
Explanation:
The amount of vapor in the air determines how humid it feels.
The amount of vapor required to make the air saturated determines the relative humidity, which affects whether the air feels dry or humid.
The temperature of the air influences the feeling of humidity because warmer air can store more water vapor.
Humidity relative to dew point temperature is 100%- Right
Ice-ball is prepared from shredded ice again. This is the example of regelation.
If pressure increases, the melting point of a substance increases.
Explanation:
Most substances' melting points rise as pressure increases because the solid state is more compact than the liquid state. Higher pressure favors the solid phase, necessitating additional heat (higher temperature) to overcome this and cause melting. Ice is an exception to this rule, as its melting point decreases under pressure due to its unusual structure.
Let maximum common temperature of mixture be T ˚C
According principle of heat exchange,
Thus, maximum temperature of mixture will be 50 ˚C.
All the above
Explanation:
Water has a peculiarity property according to which it has maximum density at around 4 degrees Celsius. As we go above or below the mark, the density decreases. Also, the density of ice is lower than that of water.
A circulation is thus set up until water in the pond reaches it is maximum density of 4 degrees Celsius.
When at atmospheric temperature reaches 0 degrees Celsius ice begins to form in ponds forming a layer on the top with water below it. If water did not have this property, then it would be impossible for aquatic life to exist in water bodies in cold seasons.
After sufficient thickness of ice is formed it prevents further loss of heat from the bottom layers of water. This is why fishes and other aquatic animals and plants can survive in ponds and other water bodies even when the atmospheric temperature reaches or is well below 0 degrees.
In cold region, as temperature reaches below 4 °C, water instead of contracting, starts expanding due to its anomalous behaviour.
As temperature decreases from 4 °C to 0 °C, volume of water increases continuously.
At the same time, metal pipes carrying water undergo contraction.
As a result, pipes experience force applied by water and break.
| Column A | Column B |
| 1) Absolute humidity | e) kg/m3 |
| 2) Latent heat | c) kJ/kg |
| 3) Specific heat capacity | b) J/kg °C |
| 4) Heat | a) J or cal |
| Column A | Column B |
| 1) Dry air | c) Relative humidity below 60% |
| 2) Humid air | d) Relative humidity above 60% |
| 3) Saturated air/Dew point temperature | b) Relative humidity 100% |
| 4) Maximum density of water | a) 4 °C |
| Column A | Column B |
| 1) Specific latent heat of fusion | b) Solid converts into liquid |
| 2) Specific latent heat of vaporisation | c) liquid converts into gas |
| 3) Dew point temperature | a) Air saturated with vapour |
The graph represents anomalous behaviour of water.
The range of temperature responsible for the behaviour is 0 °C to 4 °C.
The property we understand is: Anomalous behaviour of water.
Temperature of water at the surface is 0 °C.
Temperature just below the layer of ice on the surface is approximately 0 °C and it might increase with increasing depth.
Heat is transferred from hot object to cold object.
During the transfer of heat from hot object to cold object we perceive the principle of heat exchange.
As inside the heat resistant box, the heat lost by hot object exactly equals heat gained by cold object, principle of heat exchange is stated as:
In an isolated system,
Specific heat of the substance is measured using the principle of heat exchange.
Property which determines the amount of heat absorbed by a sphere is different for the three spheres is ascertain from this activity.
This property is called the specific heat capacity.
Relative humidity greater than 60% : humid air : : relative humidity less than 60% : dry air
Specific latent heat of vaporisation : J/kg : : specific heat : J/kg °C
Modern periodic law states that "The physical and chemical properties of all elements are a periodic function of their atomic numbers".
Principle of heat exchange can show that the energy exchange takes place between two objects only when kept in isolated system.
The density of water is high at 4 °C : anomalous behaviour of water : : shredded ice converted into solid ice balls : Regelation
The dew point temperature does not depend on the amount of vapor in the air- Wrong
The latent heat of vaporisation is a term referred for the conversion of gas into liquid- Wrong
The SI unit of specific heat is J/kg °C.
The specific heat capacity of water is 1 cal/g °C- Right
The unit of absolute humidity is kg/m3- Right
The vapour content in the air is measured using a physical quantity called absolute humidity.
All of the above
Explanation:
Fog forms when water vapor in the air condenses near the ground, forming small droplets with a cloud-like appearance.
Snowfall occurs when water vapor in cold air condenses straight into ice crystals, resulting in snowflakes.
Rainfall occurs when water vapor condenses into liquid droplets in clouds and becomes heavy enough to fall to the earth.
Existence of drops of water on leaves in the morning indicates that air is saturated with vapour.
When unsaturated air (of specific volume) at a certain temperature is taken and its temperature is decreased, a temperature is reached at which the air becomes saturated with vapour. This temperature is called the dew point temperature.
The heat energy required to change substance from one state to another at constant temperature is called as latent heat of a substance.
When latent heat is given off from a substance, it causes the strengthening of the bonds between atoms or molecules causing a change of state of the substance.
When a liquid substance gives off latent heat of fusion, strengthening of bonds results into pulling of atoms or molecules of liquid closer and eventually it changes into solid-state.
Similarly, when a gaseous substance gives off latent heat of vaporisation, strengthening of bonds results into the pulling of atoms or molecules of gas closer and eventually it changes into a liquid state.
The phenomenon in which the ice converts to liquid due to applied pressure and then re-converts to ice once the pressure is removed is called regelation.
During the winter in frigid places, the temperature of the atmosphere drops significantly below 0°C. As the temperature drops, the water on the surfaces of lakes and ponds contracts. As a result, its density rises, and it sinks to the bottom.
This process continues until the temperature of all the water in a lake drops to 4°C. As the water near the surface cools more, reaching temperatures below 4°C, it begins to expand rather than compress. As a result, its density drops, and it remains on the surface.
The temperature of the water at the surface continues to decrease to 0 degrees Celsius. Finally, the water at the surface turns into ice, but the water behind the layer of ice remains at 4°C. Ice does not transfer heat well.
As a result, the ice layer at the surface prevents heat from leaving the water and entering the atmosphere. Fish, other aquatic animals, and plants can survive in the water beneath the ice layer since the temperature remains at 4°C.
All known elements could not be classified into groups of triads on the basis of their properties.
Dobereiner could find only three triads; .i.e total of 9 elements only.
However, the total number of elements was more than that of those encompassed in Dobereiner’s Triad.
When ice is converted into water : constant temperature : : before the water evaporates : temperature is increasing
When the temperature of water decreases below 4 °C it’s volume increases.
Explanation:
The unusual expansion of water is unique. Water has greatest density and minimum volume at 4 °C. At temperatures below 4 °C, water expands, increasing its volume.
Ice floats because it is less thick than liquid water.
Valency
Principle of heat exchange is used to measure the specific heat capacity of a substance.
While deciding the unit for heat, temperature interval chosen is 14.5 °C to 15.5 °C.
Reason:
While studying anomalous behaviour of water in Hope’s apparatus, the upper temperature of the thermometer : 0 °C : : lower temperature of the thermometer : 4 °C
Normally, liquids expand on heating and contract on cooling. But water exhibits an exceptional behaviour in a temperature range of 0 °C to 4 °C.
When water is heated from 0 °C up to 4 °C, instead of expanding it contracts. Its volume decreases continuously from 0 °C to 4 °C. At 4 °C, its volume is minimum.
Upon heating further, however, it expands and its volume increases.
This behaviour of water between temperature interval of 0 °C to 4 °C is called anomalous behaviour of water.
Phenomena observed due to anomalous behaviour of water are:
Survival of aquatic life in cold regions,
Cracking of rocks in winter,
Breaking of pipes for water supply in a cold region.
When unsaturated air (of specific volume) at a certain temperature is taken and its temperature is decreased, a temperature is reached at which the air becomes saturated with vapour. This temperature is called the dew point temperature.
Relative humidity of air at dew point is 100%.
Dew drops, condensation of water droplets on the surface of water bottle taken out from refrigerator are some visible examples of air having reached dew point temperature.
The phenomenon in which the ice converts to liquid due to applied pressure and then re-converts to ice once the pressure is removed is called regelation.
Due to applied pressure, the melting point of ice is lowered below 0 °C. As a result, ice gets converted into water at 0 °C.
When the applied pressure is removed, the melting point is restored to 0 °C and water gets re-converted into ice.
Preparation of ice balls uses phenomenon of regelation. The shredded ice is pressurised around the tip of the stick and then due to regelation gets re-freezed in the form of a single solid ice ball.
The amount of heat energy required to raise the temperature of a unit mass of an object by 1 °C is called the specific heat or specific heat capacity of that object.
SI unit of specific heat capacity is J/kg °C and CGS unit is cal/g °C
Specific heat is a property of a substance and is different for different substances.
Higher the value of specific heat capacity of the substance, higher is the amount of heat energy required to raise its temperature by 1 °C.
The specific heat capacity of object is measured using principle of heat exchange.
The ratio of actual mass of vapour content in the air for a given volume and temperature to that required to make the air saturated with vapour at that temperature is called relative humidity.
The white trail is basically the vapour released by aeroplane engine condensing in sky to form a cloud.
If the relative humidity of surrounding air is more then, we may get to observe this white trail at the back of the aeroplane flying high in the clear sky.
If the relative humidity of surrounding air is less then, either small sized white trail may get formed or it may not get formed at all.
The heat energy absorbed at a constant temperature during transformation of liquid into a gas is called the latent heat of vaporisation.
When heat is supplied to boiling water, it is used to weaken the bonding between molecules of water, causing transformation from liquid state to gaseous state, i.e., steam.
As the heat supplied is utilized for the change of state entirely, temperature of water does not change.
When the wire with weights attached to its two ends is placed on the ice slab, its weight acts along very small area of contact between the wire and ice.
As a result, pressure gets applied on that part of ice-slab.
This lowers the melting point of ice below 0 °C and ice is converted into water.
The wire cuts through water and shifts downward.
As the wire displaces, pressure applied by wire on ice slab vanishes and its melting point is restored to 0 °C causing freezing of ice.
In this manner, due to regelation wire moves through the ice slab completely without breaking it.
In cold climate, temperature of water in ponds and lakes starts falling.
On getting colder, water contracts. As a result, the density of water increases and it goes down. To replace it, warmer water from below rises up.
This process continues till temperature of water at the bottom of pond becomes 4 °C.
Water, due to its anomalous behaviour possesses maximum density at 4 °C.
If the temperature lowers further, ice is formed at the surface of a pond with water below it.
Ice is a poor conductor of heat blocks the further heat exchange between the atmosphere and water in the pond.
This prevents freezing of water below surface of ponds or lakes enabling survival of fishes.
Snow is formed high in the clouds from water vapour.
In cold regions when the temperature is extremely low, water vapour freezes around smoke or dust particles forming ice crystals.
When these ice particles combine with each other they turn heavy and start falling to the ground.
This gives rise to snowfall in cold regions in winter.
Temperature of the freezer section in a refrigerator is maintained below 0 °C.
When a plastic bottle filled completely with water is placed in the freezer, the temperature of water starts falling down.
When the temperature of water reaches 4 °C, due to its anomalous behaviour, water starts expanding.
As the temperature of water continues to fall upto 0 °C, water continues to expand. When water is converted into ice at 0 °C, there is an increase in the volume.
This exerts pressure on the sides of the bottle. As a result, there is a probability of breaking or exploding of the bottle.
Copper is a better conductor of heat as compared to steel.
Also, copper can conduct faster than steel.
As a result, copper bottom gets heated faster than steel.
This reduces the time for cooking as well as saves heat energy and fuel.
Normally, in cold air, more heat energy needs to be supplied to attain high temperatures required for cooking food. It also consumes more time.
Whereas, pressure cooker operates by giving out the air within the cooker and trapping steam produced from the liquid, (mostly water) boiling inside.
Due to high internal pressure, boiling point of liquid increases and liquid boils at temperature higher than its boiling point.
The increased boiling point allows more absorption of heat by liquid and steam formed is superheated causing food to get cooked quickly.
Conversion of ice into liquid due to applied pressure and the reconverts to ice once the pressure is removed- Regelation
Products obtained when sugar is heated- Carbon and water vapour
The amount of heat absorbed at constant temperature by unit mass of a liquid to convert into gaseous phase- Specific latent heat of vaporisation
The instrument used to measure the specific heat capacity of a substance using mixture method- Calorimeter
The instrument used to study anomalous behaviour of water- Hope’s apparatus
The phase in which solid substances are converted into liquid- Melting