Sign in
12thPass logo
New chatPYQ LibraryDoubtsRank report
Sign in to see Recents

Your guest activity stays on this device

Sign in to save progress →
Sign in

Heat and Thermodynamics question

2020 · 4 Sep · Shift 1 · Q56
Guest · filters and generic practice availableBrowsing as a guest · PYQ filters and generic practice are available. Sign in only for personalised features and saved progress.
  1. PYQ Library
  2. /JEE Main
  3. /Physics
  4. /Heat and Thermodynamics
  5. /2020 · 4 Sep · Shift 1 · Q56

Heat and Thermodynamics question

2020 · 4 Sep · Shift 1 · Q56

JEE MainPhysicsHeat and ThermodynamicsMCQ+4 / −1
The specific heat of water = 4200 J kg-1K-1 and the latent heat of ice = 3.4 ×\times× 105 J kg–1. 100 grams of ice at 0oC is placed in 200 g of water at 25oC. The amount of ice that will melt as the temperature of water reaches 0oC is close to (in grams) :
  1. A
    63.8
  2. B
    61.7
  3. C
    69.3
  4. D
    64.6
View written solutionFree

Correct answer: B

  1. Given data
  • Mass of ice: mi=100 g=0.1 kgm_i = 100\text{ g} = 0.1\text{ kg}mi​=100 g=0.1 kg at 0∘C0^\circ\text{C}0∘C
  • Mass of water: mw=200 g=0.2 kgm_w = 200\text{ g} = 0.2\text{ kg}mw​=200 g=0.2 kg at 25∘C25^\circ\text{C}25∘C
  • Specific heat of water: c=4200 J kg−1K−1c = 4200\,\text{J kg}^{-1}\text{K}^{-1}c=4200J kg−1K−1
  • Latent heat of fusion of ice: L=3.4×105 J kg−1L = 3.4 \times 10^5\,\text{J kg}^{-1}L=3.4×105J kg−1

We need the amount of ice melted when the final temperature becomes 0∘C0^\circ\text{C}0∘C.


  1. Heat lost by water in cooling from 25∘C25^\circ\text{C}25∘C to 0∘C0^\circ\text{C}0∘C

Q=mwcΔTQ = m_w c \Delta TQ=mw​cΔT

Q=0.2×4200×25Q = 0.2 \times 4200 \times 25Q=0.2×4200×25

Q=21000 JQ = 21000\,\text{J}Q=21000J


  1. This heat is used to melt some ice at 0∘C0^\circ\text{C}0∘C

If mass melted is mmm, then

Q=mLQ = mLQ=mL

So,

m=QL=210003.4×105m = \frac{Q}{L} = \frac{21000}{3.4 \times 10^5}m=LQ​=3.4×10521000​

m=0.06176 kgm = 0.06176\,\text{kg}m=0.06176kg

Converting to grams:

m=61.76 gm = 61.76\,\text{g}m=61.76g


  1. Closest option

m≈61.7 gm \approx 61.7\,\text{g}m≈61.7g

So the correct option is B.


  1. Comparison with stored answer

Stored correct answer: B

Our derived answer: B

They agree.

PreviousNext

More from Heat and Thermodynamics

  • A closed vessel contains 0.1 mole of a monoatomic ideal gas at 200 K. If 0.05 mole of the same gas at 400 K is added to it, the final equilibrium temperature (in K) of the gas in the vessel will be close to ​.2020 · Numerical
  • The change in the magnitude of the volume of an ideal gas when a small additional pressure Δ P is applied at a constant temperature, is the same as the change when the temperature is reduced by a small quantity Δ T at…2020 · Numerical
  • Match the thermodynamic processes taking place in a system with the correct conditions. In the table : Δ Q is the heat supplied, Δ W is the work done and Δ U is change in internal energy of the system. Includes table2020 · MCQ
  • A bullet of mass 5 g, travelling with a speed of 210 m/s, strikes a fixed wooden target. One half of its kinetic energy is converted into heat in the bullet while the other half is converted into heat in the wood. The rise of temperature…2020 · MCQ
  • Number of molecules in a volume of 4 cm3 of a perfect monoatomic gas at some temperature T and at a pressure of 2 cm of mercury is close to? (Given, mean kinetic energy of a molecule (at T) is 4 × 10–14 erg, g = 980 cm/s2, density…2020 · MCQ
  • Three different processes that can occur in an ideal monoatomic gas are shown in the P vs V diagram. The paths are labelled as A → B, A → C and A → D. The change in internal energies during these process are taken as EAB, EAC… Includes diagram2020 · MCQ
  • Nitrogen gas is at 300oC temperature. The temperature (in K) at which the rms speed of a H2 molecule would be equal to the rms speed of a nitrogen molecule, is ​. (Molar mass of N2 gas 28 g).2020 · Numerical
  • In an adiabatic process, the density of a diatomic gas becomes 32 times its initial value. The final pressure of the gas is found to be n times the initial pressure. The value of n is :2020 · MCQ