Question 1 :
The convection current continues till the entire medium acquires the ________ density.

Question 3 :
The temperature of a body is 3000K. The wavelength corresponding to maximum emission of radiation will be <br>

Question 4 :
A thermometer has a low thermal capacity. Why is this an advantage?

Question 5 :
Heat is added to a block of ice of mass $m$ until the entire block melts into liquid water.&#160;Identify by which of the following method this can be explained ?

Question 6 :
A beaker full of hot water is kept in a room. If it cools from ${80}^{o}C$ to ${75}^{o}C$ in ${t}_{1}$ minutes, from ${75}^{o}C$ to ${70}^{o}C$ in ${t}_{2}$ minutes and from ${70}^{o}C$ to ${65}^{o}C$ in ${t}_{3}$ minutes, then

Question 7 :
A bullet moving with a uniform velocity v, stops suddenly after hitting the target and the whole mass melts be m, specific heat S, initial temperature $25^oC$, melting point $475^oC$ and the latent heat L. Then v is given by-

Question 8 :
Hot water cools from $60^oC$ to $50^oC$ in the first $10$ minutes and to $42^oC$ in the next $10$ minutes. The temperature of the surroundings is :

Question 9 :
If the temperature of water changes by $15^o C$ on giving $300 \,cal$ of heat, what is the mass of water?

Question 10 :
There are two solar energy collectors made up of thin aluminium sheet. They are flat and uncoated. Collector '$A$'&#160;is rectangular measuring $20$ cm long and $15$ cm wide while collector '$B$' is circular having $20$ cm diameter. If they&#160;are kept under mid-day sun for long time then,<br/>

Question 11 :
A body of length $1m$ having a cross-sectional area $0.75m^2$ has heat flow through it at the rate of $6000 \ Joule/sec$. Then find the temperature difference if $K=200Jm^{-1}K^{-1}$

Question 12 :
If the maximum emission wavelength of radiations emitted by the moon and the sun are $10^{-4}$ m and $0.5\space \times \space 10^{6}$ m respectively, then the ratio of temperature of the sun and moon will be<br>

Question 13 :
Three rods A,B and C have the same dimensions.Their conductivities are $K_{A}, K_{B}$ and $ K_{C}$ respectively. A and B are placed end to end, with their free ends kept at certain temperature difference. C is placed separately with its ends kept at same temperature difference. The two arrangements conduct heat at the same rate $K_{c}$ must be equal to

Question 14 :
Two bodies have thermal capacities in the ratio&#160;3 : 4 and the rates of loss of heat in the ratio&#160;3 : 5. Their rates of cooling will be in the ratio of :

Question 15 :
Sublimation is the process of separating a liquid from its solution by evaporating it and then condensing its vapour.

Question 16 :
An aluminium measuring rod, which is correct at $5^o C $ measures the length of a line as $80 cm $ at $45^o C $ . If thermal coefficient of linear expansion of aluminium is $2.50 \times 10^{-5} per^o C $ .The correct length of line is :

Question 17 :
Two identical rods of a mental are welded in series then 20 cal of heat flows through them in 4 minute. If the rods are welded in parallel then same amount of heat will flow in

Question 18 :
A glass vessel of volume $100\;cm^3$ is filled with mercury and is heated from $25^{\circ}C\;to\;75^{\circ}C$. What volume of mercury will overflow? Coefficient of linear expansion of glass $=1.8\times10^{-6}/^{\circ}C$ and coefficient of volume expansion of mercury is $1.8\times10^{-4}/^{\circ}C$.

Question 19 :
A concrete sphere of radius $R$ has a cavity of radius $r$ which is placed with sawdust$.$ The specific gravities of concrete and sawdust are respectively $2.4$ and $0.3$ for this sphere to float with its entire volume submerged under water$.$ Ratio of mass of concrete to mass of sawdust will be

Question 20 :
A thermocol box has a total wall area (including the lid) of $1.0{ m }^{ 2 }$ and wall thickness of $3cm$. It is filled with ice at ${ 0 }^{ o }C$. If the average temperature outside the box is ${ 30 }^{ o }C$ throughout the day, the amount of ice that melts in one day is<br>(Use ${ K }_{ thermocol }=0.03W/mK,{ L }_{ fusion(ice) }=3.00\times { 10 }^{ 5 }J/kg\quad $