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Thermos flask can control the transfer of heat (loss of heat) and retain hotness of tea for a few hours.

1) The process of transfer of heat from hotter to colder end through the conductor is called conduction. This mode of transfer of heat happens more in solid conductors. 

2) Example 1: 

It takes some time for the heat to reach the end of the spatula placed in the cooking vessel. The heat from cooking vessel transfers to the end of the spatula gradually. This type of heat transfer is called conduction. 

3) Example 2: 

The edges of the steel plate with burning coal burn our hand while holding it. Here the heat transfers from the middle of the plate to the edges gradually. 

4) Example 3: 

If we put a needle by holding it in the candle flame, it causes burn to our hand. It is due to conduction of heat. 

The average kinetic energy of the molecules is directly proportional to the absolute temperature.

They do not have sweat glands for evaporation process. So pigs toil in the mud.

The vapour may come from evaporation of water from the surfaces of rivers, lakes, ponds, and from the drying of wet clothes, sweat, and so on.

We can feel the heat of table lamp under it because every warm substance continuously emits heat in all directions around itself by radiation.

White clothes do not absorb heat but reflect back therefore cricketers wear white clothes while playing in the sun.

Sawdust is a bad conductor of heat because heat travels very slowly through it.

Aluminium is a good conductor of heat.

Good conductors — Mercury, copper, silver, iron. Bad conductors — Wood, air, saw dust, plastic, wool, cardboard.

Kinetic energy: The energy possessed by a body by virtue of its motion.

KE = \(\frac12\)mv² or \(\frac32\)RT

Joule: The unit of energy of work. 1 joule of work is done when a force of 1 Newton moves through 1 meter.

James Prott Joule (18181 1889):

Joule was a British physicist, famous for his research into electricity and thermodynamics.

In 1840, he sent a paper entitled on the Production of Heat by Voltaic Electricity to the prestigious Royal Society in London.

In 1843 Joule calculated the amount of mechanical work needed to produce an equivalent amount of heat. This quantity was called the mechanical equivalent of heat.

The principle of energy conservation involved in Joule’s work gave rise to the new scientific discipline known as thermodynamics.

He died at Sale, Cheshire, England, on October 11, 1889.

The SI unit for amount of heat is named in Joule’s honor

Evaporation : 

The process of escaping of molecules from the surface of liquid at any temperature is called evaporation. 

The affecting factors of evaporation : 

1. Temperature, 

2. Surface area, 

3. Wind speed, 

4. Humidity.

The affection on the rate of evaporation : 

1) Temperature : As the temperature increases evaporation increases. 

2) Surface area : As the surface area of liquid increases, more molecules tend to leave the surface. So rate of evaporation increases. 

3) Wind speed : As the wind speed increases rate of evaporation increases. 

4) Humidity : As the humidity increases rate of evaporation decreases.

Correct option is  B) 0° C

D) water vapour at 100° C

Correct Answer is: (a, b, c, & d)

D) average kinetic energy

Correct Answer is: ( b, d)

Correct Answer is: (a, b, & d)

Correct Answer is: (a) conservation of energy, (d) equivalence of heat and work

Correct Answer is: (b, d)

Correct Answer is: (b)

Correct Answer is: (c)

Correct Answer is: (c)

Correct Answer is: ( a, b, & c)

In a cyclic process, heat is absorbed by a gas when the work done by it is positive, i.e., when work is done by the gas.

Correct Answer is: (c) π/4 ( p₂ - p₁)(V₂ - V₁)

For a cyclic process plotted on the p–V diagram, the work done = area inside the closed curve. Treat the circle as an ellipse of semimajor axis 1/2 (p₂ - p₁) and semiminor axis 1/2 (V₂ - V₁).

Yes. when the ice melts, heat is absorbed, but the temperature does not change. Also, when water refreezes, heat is given out, but the temperature does not change. This heat absorbed or given out is the latent heat.

When the thin wire with two equal weights attached to its ends is hung over the block of ice, it exerts pressure on the ice below it. Due to this, the melting point of the ice below the wire is lowered and some ice melts. The wire passes through the water so formed.

The water above the wire is no longer under pressure and, therefore, refreezes. Once again the ice below the wire melts, and the wire passes through it, and the process continues. In this way, due to alternate melting of ice and refreezing of water, the wire cuts right through the block of ice leaving the block intact.

Answer is Yes.

During these transformations, the latent heat is given out by the substance to the surroundings.

Correct option is   D) \(\overline{DE}\)

Correct option is  D) 730 cal