Assertion: It is hotter over the top of a fire than at the same distance of the side. 
Reason: Air surrounding the fire conducts, more heat upward.

1. If both the assertion and the reason are true and the reason is a correct explanation of the assertion
2. If both the assertion and reason are true but the reason is not a correct explanation of the assertion
3. If the assertion is true but the reason is false
4. If both the assertion and reason are false

In a new temperature scale, freezing point of water is given a value $10\mathrm{x}$ and boiling point of water is $90\mathrm{x}$. Reading of new temperature scale for a temperature equal to $10°\mathrm{C}$ is 

1.  $14\mathrm{x}$

2.  $16\mathrm{x}$

3.  $18\mathrm{x}$

4.  $12\mathrm{x}$

The temperature of a body on the Kelvin scale is found to be \(x^\circ~\text K.\) When it is measured by a Fahrenheit thermometer, it is found to be \(x^\circ~\text F,\) then the value of \(x\) is:
1. \(40\)
2. \(313\)
3. \(574.25\)
4. \(301.25\)

A black body at \(227^{\circ}~\mathrm{C}\) radiates heat at the rate of \(7~ \mathrm{cal-cm^{-2}s^{-1}}\).  At a temperature of \(727^{\circ}~\mathrm{C}\), the rate of heat radiated in the same units will be:
1. \(60\)
2. \(50\)
3. \(112\)
4. \(80\)

The two ends of a rod of length L and a uniform cross-sectional area A are kept at two temperatures T₁ and T₂ (T₁> T₂). The rate of heat transfer $\frac{\mathrm{dQ}}{\mathrm{dt}}$ through the rod in a steady state is given by:

1. $\frac{\mathrm{dQ}}{\mathrm{dt}}=\frac{\mathrm{KL}({\mathrm{T}}_1-{\mathrm{T}}_2)}{\mathrm{A}}$

2. $\frac{\mathrm{dQ}}{\mathrm{dt}}=\frac{\mathrm{K}({\mathrm{T}}_1-{\mathrm{T}}_2)}{\mathrm{LA}}$

3. $\frac{\mathrm{dQ}}{\mathrm{dt}}=\mathrm{KLA}({\mathrm{T}}_1-{\mathrm{T}}_2)$

4. $\frac{\mathrm{dQ}}{\mathrm{dt}}=\frac{\mathrm{KA}({\mathrm{T}}_1-{\mathrm{T}}_2)}{\mathrm{L}}$

Assuming the sun to have a spherical outer surface of radius \(r,\) radiating like a black body at temperature \(t^\circ \text{C},\) the power received by a unit surface of the earth (normal to the incident rays) at a distance \(R\) from the centre of the sun will be:
(where \(\sigma\) is Stefan's constant)

A black body is at \(727^\circ\text{C}.\) The rate at which it emits energy is proportional to:

A black body at \(1227^\circ\text{C}\) emits radiations with maximum intensity at a wavelength of \(5000~\mathring {A}\). If the temperature of the body is increased by \(1000^\circ\text{C},\) the maximum intensity will be observed at:
1. \(4000~\mathring {A}\)
2. \(5000~\mathring {A}\)
3. \(6000~\mathring {A}\)
4. \(3000~\mathring {A}\)

A copper rod of \(88\) cm and an aluminium rod of an unknown length have an equal increase in their lengths independent of an increase in temperature. The length of the aluminium rod is:
\(\left(\alpha_{Cu}= 1.7\times10^{-5}~\text{K}^{-1}~\text{and}~\alpha_{Al}= 2.2\times10^{-5}~\text{K}^{-1}\right)\)
1. \(68~\text{cm}\)
2. \(6.8~\text{cm}\)
3. \(113.9~\text{cm}\)
4. \(88~\text{cm}\)