List of top Physics Questions on CHANGE OF STATE

When ice at $0^\circ\text{C}$ is heated and converted into steam at $100^\circ\text{C}$, which graph correctly represents the variation of temperature with heat supplied?
A modulating signal 2sin (6.28 × 106) t is added to the carrier signal 4sin(12.56 × 109) t for amplitude modulation. The combined signal is passed through a non-linear square law device. The output is then passed through a band pass filter. The bandwidth of the output signal of band pass filter will be ______MHz.
1g of water, of volume 1 cm$^3$ at 100?C, is converted into steam at same temperature under normal atmospheric pressure ($\simeq$ ) $1\times 10^5$Pa . The volume of steam formed equals 1671 cm$^3$. If the specific latent heat of vaporisation of water is 2256 J/g, the change in internal energy is,
Saturated vapour is compressed to half its volume without any change in temperature, then the pressure will be
A ‘thermacole’ icebox is a cheap and efficient method for storing small quantities of cooked food in summer in particular. A cubical icebox of side 30 cm has a thickness of 5.0 cm. If 4.0 kg of ice is put in the box, estimate the amount of ice remaining after 6 h. The outside temperature is 45 °C, and coefficient of thermal conductivity of thermacole is 0.01 J s–1 m–1 K–1. [Heat of fusion of water = 335 × 103 J kg–1]
A child running a temperature of 101°F is given an antipyrin (i.e. a medicine that lowers fever) which causes an increase in the rate of evaporation of sweat from his body. If the fever is brought down to 98°F in 20 minutes, what is the average rate of extra evaporation caused, by the drug. Assume the evaporation mechanism to be the only way by which heat is lost. The mass of the child is 30 kg. The specific heat of human body is approximately the same as that of water, and latent heat of evaporation of water at that temperature is about 580 cal g–1.
Explain why :
  1. a body with large reflectivity is a poor emitter
  2. a brass tumbler feels much colder than a wooden tray on a chilly day
  3. an optical pyrometer (for measuring high temperatures) calibrated for an ideal black body radiation gives too low a value for the temperature of a red hot iron piece in the open, but gives a correct value for the temperature when the same piece is in the furnace
  4. the earth without its atmosphere would be inhospitably cold
  5. heating systems based on circulation of steam are more efficient in warming a building than those based on circulation of hot water