JEE Main 2025 January Physics: Thermal Properties of Matter – Previous Year Questions

An amount of ice of mass $10^{-3}$ kg and temperature $-10^\circ$C is transformed to vapour of temperature $110^\circ$C by applying heat. The total amount of work required for this conversion is, (Take, specific heat of ice $= 2100\ \mathrm{Jkg^{-1}K^{-1}}$, specific heat of water $= 4180\ \mathrm{Jkg^{-1}K^{-1}}$, specific heat of steam $= 1920\ \mathrm{Jkg^{-1}K^{-1}}$, Latent heat of ice $= 3.35\times10^{5}\ \mathrm{Jkg^{-1}}$ and Latent heat of steam $= 2.25\times10^{6}\ \mathrm{Jkg^{-1}}$)

A gun fires a lead bullet of temperature 300 K into a wooden block. The bullet having melting temperature of 600 K penetrates into the block and melts down. If the total heat required for the process is 625 J, then the mass of the bullet is grams. (Latent heat of fusion of lead $= 2.5\times10^{4}\ \mathrm{JKg^{-1}}$ and specific heat capacity of lead $= 125\ \mathrm{JKg^{-1}K^{-1}}$)

The temperature of a body in air falls from $40^\circ$C to $24^\circ$C in 4 minutes. The temperature of the air is $16^\circ$C. The temperature of the body in the next 4 minutes will be :

Which of the following figure represents the relation between Celsius and Fahrenheit temperatures ?

Two spherical bodies of same materials having radii 0.2 m and 0.8 m are placed in same atmosphere. The temperature of the smaller body is 800 K and temperature of the bigger body is 400 K. If the energy radiated from the smaller body is $E$, the energy radiated from the bigger body is (assume, effect of the surrounding temperature to be negligible),

Three conductors of same length having thermal conductivity $k_1$, $k_2$ and $k_3$ are connected as shown in figure. Area of cross sections of $1^{st}$ and $2^{nd}$ conductor are same and for $3^{rd}$ conductor it is double of the $1^{st}$ conductor. The temperatures are given in the figure. In steady state condition, the value of $\theta$ is $^\circ$C. (Given : $k_1 = 60\ \mathrm{Js^{-1}m^{-1}K^{-1}}$, $k_2 = 120\ \mathrm{Js^{-1}m^{-1}K^{-1}}$, $k_3 = 135\ \mathrm{Js^{-1}m^{-1}K^{-1}}$)

A cup of coffee cools from $90^\circ$C to $80^\circ$C in $t$ minutes when the room temperature is $20^\circ$C. The time taken by the similar cup of coffee to cool from $80^\circ$C to $60^\circ$C at the same room temperature is :