Thermal energy Quiz 1

Question 1

A coal-fired power plant generates $$6\,KW$$ of energy per second; if the calorific value of coal is $$1000\,\,Joule/kg$$ the amount of coal needed to operate this plant for one minute is $$(	ext{efficiency of plant is 60%})$$

Accepted Answer

$$600\,kg$$

Answer

$$10\,kg$$

Answer

$$100\,kg$$

Answer

$$1200\,kg$$

Question 2

$$1\,kg$$ of ice is kept in a glen jar at $${{0}^{\circ }}C$$ in order to make it completely water at $${{0}^{\circ }}C$$ by using some water at $${{10}^{\circ }}C$$ . How much water will be required to melt the ice at  $${{10}^{\circ }}C$$? $${{L}_{fusionice}}=332\dfrac{J}{g}$$, $${{C}_{water}}=4.2\dfrac{J}{g{{m}^{\circ }}C}$$

Accepted Answer

$$7904\,g$$

Answer

$$5000\,g$$

Answer

$$6950\,g$$

Answer

$$9000\,g$$

Question 3

$$10\,kg$$ ice is kept at a height $$''H''$$. Ice thrown from this height loses its potential energy resulting in melting of ice.  Find the height  $$''H''$$? $$({L_{ice}}=336{J}/{gm})$$

Accepted Answer

$$33.6\,m$$

Answer

$$42.3\,m$$

Answer

$$15\,m$$

Answer

$$20.3\,m$$

Question 4

If the pressure in an isothermal process is increased by $$20\%$$, the change in volume would be?

Accepted Answer

$$20\%$$ decrease

Answer

$$10\%$$ increase

Answer

$$10\%$$ decrease

Answer

$$20\%$$ increase

Question 5

A gas is filled and held isothermally in a closed fixed container. The pressure exerted by the gas is $${{P}_{o}}$$. If  $$\dfrac{3}{4}^{th}$$ of the mass of gas is removed, then what is the new pressure inside the container?

Accepted Answer

$$\dfrac{1}{4}{{P}_{o}}$$

Answer

$${{P}_{o}}$$

Answer

$$\dfrac{3}{4}{{P}_{o}}$$

Answer

zero