The value of the coefficient of volume expansion of glycerine is $$5\times10^{-4} \mathrm{~K^{-1}}$$. The fractional change in the density of glycerine for a rise of $$40^\circ \text{C}$$ in its temperature is:
1. $$0.015$$
2. $$0.020$$
3. $$0.025$$
4. $$0.010$$

Subtopic:  Thermal Expansion |
81%
From NCERT
NEET - 2015
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On observing light from three different stars $$P$$, $$Q$$, and $$R$$, it was found that the intensity of the violet colour is maximum in the spectrum of $$P$$, the intensity of the green colour is maximum in the spectrum of $$R$$ and the intensity of the red colour is maximum in the spectrum of $$Q$$. If $$T_P$$$$T_Q$$, and $$T_R$$ are the respective absolute temperatures of $$P$$, $$Q$$, and $$R$$, then it can be concluded from the above observations that:
1. $$T_P>T_Q>T_R$$
2. $$T_P>T_R>T_Q$$
3. $$T_P<T_R<T_Q$$
4. $$T_P<T_Q<T_R$$

Subtopic:  Wien's Displacement Law |
65%
From NCERT
NEET - 2015
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The two ends of a metal rod are maintained at temperatures $$100~^\circ\text{C}$$ and $$110~^\circ\text{C}.$$ The rate of heat flow in the rod is found to be $$4.0$$ J/s. If the ends are maintained at temperatures $$200~^\circ \text{C}$$ and $$210 ~^\circ \text{C},$$ the rate of heat flow will be:
1. $$44.0$$ J/s
2. $$16.8$$ J/s
3. $$8.0$$ J/s
4. $$4.0$$ J/s

Subtopic:  Conduction |
83%
From NCERT
NEET - 2015
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Steam at $$100~^{\circ}\mathrm{C}$$ is passed into $$20~\text{g}$$ of water at $$10~^{\circ}\mathrm{C}$$. When water acquires a temperature of $$80~^{\circ}\mathrm{C}$$, the mass of water present will be:
[Take specific heat of water $$= 1~\text{cal g}^{-1}~^\circ\mathrm{C}^{-1}$$ and latent heat of steam $$= 540~\text{cal g}^{-1}$$]
1. $$24~\text{g}$$
2. $$31.5~\text{g}$$
3. $$42.5~\text{g}$$
4. $$22.5~\text{g}$$

Subtopic:  Calorimetry |
69%
From NCERT
AIPMT - 2014
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A certain quantity of water cools from $$70~^{\circ}\text{C}$$ to $$60~^{\circ}\text{C}$$ in the first $$5$$ minutes and to $$54~^{\circ}\text{C}$$ in the next $$5$$ minutes. The temperature of the surroundings is:
1. $$45~^{\circ}\text{C}$$
2. $$20~^{\circ}\text{C}$$
3. $$42~^{\circ}\text{C}$$
4. $$10~^{\circ}\text{C}$$

Subtopic:  Newton's Law of Cooling |
76%
From NCERT
AIPMT - 2014
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A piece of iron is heated in a flame. It first becomes dull red, then becomes reddish yellow and finally turns to white-hot. The correct explanation for the above observation is possible by using:
1. Wien’s displacement Law
2. Kirchoff’s Law
3. Newton’s Law of cooling
4. Stefan’s Law
Subtopic:  Wien's Displacement Law |
82%
From NCERT
AIPMT - 2013
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Two metal rods $$1$$ and $$2$$ of same lengths have the same temperature difference between their ends. Their thermal conductivities are $${K}_1$$ and $${K}_2$$ and cross-sectional areas $${A}_{1}$$ and $${A}_{2},$$ respectively. If the rate of heat conduction in $$1$$ is four times that in $$2,$$ then:
1. $$K_1 A_1=4K_2 {A}_2$$
2. $$K_1 {A}_1=2 {K}_2 {A}_2$$
3. $$4 {K}_1{A}_1={K}_2 {A}_2$$
4. $${K}_1 {A}_1={K}_2 {A}_2$$
Subtopic:  Conduction |
75%
From NCERT
NEET - 2013
Hints

The density of water at $$20^\circ \text{C}$$ is $$998$$ kg/m3 and at $$40^\circ \text{C}$$ is $$992$$ kg/m3. The coefficient of volume expansion of water is:
1. $$3 \times 10^{-4} / ^\circ\text C$$
2. $$2 \times 10^{-4} / ^\circ\text C$$
3. $$6 \times 10^{-4} / ^\circ\text C$$
4. $$10^{-4} / ^\circ\text C$$
Subtopic:  Thermal Expansion |
71%
From NCERT
NEET - 2013
Hints

If the radius of a star is $$R$$ and it acts as a black body, what would be the temperature of the star at which the rate of energy production is $$Q$$?
1. $$\frac{Q}{4\pi R^2\sigma}$$
2. $$\left(\frac{Q}{4\pi R^2\sigma}\right )^{\frac{-1}{2}}$$
3. $$\left(\frac{4\pi R^2 Q}{\sigma}\right )^{\frac{1}{4}}$$
4. $$\left(\frac{Q}{4\pi R^2 \sigma}\right)^{\frac{1}{4}}$$

Subtopic:  Stefan-Boltzmann Law |
83%
From NCERT
AIPMT - 2012
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Liquid oxygen at $$50$$ K is heated up to $$300$$ K at a constant pressure of $$1$$ atm. The rate of heating is constant. Which one of the following graphs represents the variation of temperature with time?

 1 2 3 4
Subtopic:  Calorimetry |
81%
From NCERT
AIPMT - 2012
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