Physics

Thermal Properties of Matter

302 Questions

Thermal properties of matter examine how substances react to heat, covering concepts like temperature, specific heat, and phase changes. This topic is regularly tested in the physics and general science sections of competitive exams. Use this collection to solve numericals on heat transfer, thermal equilibrium, and melting points.

Heat transfer and mixingMelting and freezing pointsThermal expansion and densityTriple point of waterCarnot cycle applications

Thermal Properties of Matter Questions

Multiple choice

What must molecules do in order to transfer thermal energy

  1. They must have high concentrations

  2. They must break bonds

  3. They must collide with another molecules
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Thermal energy transfer, particularly in conduction, occurs through the kinetic energy exchange between particles. This requires physical contact or collisions between molecules.

Multiple choice

What can make particles move faster?

  1. A reaction

  2. Free cookies

  3. Fire

  4. Thermal energy
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Thermal energy is the energy of motion of particles. Adding thermal energy (heat) increases the kinetic energy of particles, causing them to move faster.

Multiple choice physics temperature and heat modes of heat transfer - conduction conduction heat and modes of heat transfer

Heat required to convert one gram of ice at $0^{ _-^0}C$ into steam at $100^{ _-^0}C$ is (given $L _{steam}$ = 536 cal/gm)-

  1. 100 calorie

  2. 0.01 kilocalorie

  3. 716 calorie

  4. 1 kilocaorie
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Heat = (m * L_fusion) + (m * c_water * dT) + (m * L_vaporization). For 1g: (1 * 80) + (1 * 1 * 100) + (1 * 536) = 80 + 100 + 536 = 716 calories.

Multiple choice physics temperature and heat modes of heat transfer - conduction conduction heat and modes of heat transfer

In the Arctic region hemispherical houses called Igloos are made of ice. It is possible to maintain a temperature inside an Igloo as high as $20^o$C because.

  1. Ice has high thermal conductivity

  2. Ice has low thermal conductivity

  3. Ice has high specific heat

  4. Ice has higher density than water
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

ice is good at trapping heat. It is a  good insulator and low thermal conductivity .

Multiple choice physics temperature and heat modes of heat transfer - conduction conduction heat and modes of heat transfer

The number of quanta of radiation of frequency $4.98 \times {10^{14}}{s^{ - 1}}$ required to melt 100 g of ice are (latent heat of melting of ice is 33 joule per g):

  1. ${10^{20}}$
  2. ${10^{22}}$
  3. ${10^{24}}$
  4. $6.023 \times {10^{21}}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$1g$ requires $33J$. So, $100g$ will require $3300J$ heat.

Total quanta, 
E=hv
$=6.62\times { 10 }^{ -34 }\times 4.98\times { 10 }^{ 14 }\ =32.97\times { 10 }^{ -20 }$
$100g$ of ice will require=$\dfrac { 3300 }{ 32.97\times { 10 }^{ -20 } } =100.09$
$100$quantal=${ 10 }^{ 22 }J$

Multiple choice chemistry matter in our surroundings diffusion in different states of matter properties of solids, liquid, and gas particle theory of matter

As the water heats up from 280 K to 310 K, the average kinetic energy of its molecules will:

  1. increase

  2. decrease

  3. stay the same

  4. increase, then decrease

  5. decrease, then increase
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$T$ $\alpha$  $KE$
Higher the temperature higher will be kinetic energy .
Hence, as the water heats up from 280 K to 310 K, the average kinetic energy of the its molecules will increase.

Multiple choice physics option b: engineering physics conversion of heat into work: heat engine and it's efficiency engines and cycles refrigerators and heat pumps

An ideal refrigerator operates according to the reverse Carnot cycle and transmits heat from a cold source with water at a temperature of $27^{\circ}C$ to a boiler with water at a temperature of $100^{ \circ  }C$. What amount of water must be frozen in the cooler to convert 1 kg of water into vapor in the boiler ?

  1. 4.94 kg

  2. 3.24 kg

  3. 5.63 kg

  4. 2.12 kg
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The coefficient of performance (COP) for a Carnot refrigerator is T_cold / (T_hot - T_cold). With T_cold = 300K and T_hot = 373K, COP = 300 / 73 = 4.11. Heat removed from cold source (Q_cold) = COP * Work. Heat added to hot source (Q_hot) = Q_cold + Work = Work * (COP + 1). To convert 1 kg of water to vapor requires 2260 kJ. Using the ratio of heat transfer, the mass of ice frozen is calculated based on the latent heat of fusion (334 kJ/kg).

Multiple choice biology human influences on the environment effects of water pollution effect of water pollution water pollution and its control

For how long and at what temperature an experiment is run to determine the value of BOD of a water body? 

  1. $10^oC$ for 10 days
  2. $20^oC$ for 5 days
  3. $20^oC$ for 2 days
  4. $5^oC$ for 20 days
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

BOD or biochemical oxygen demand is the amount of dissolved oxygen which is required by the aerobic organisms during the decomposition of organic matter. The BOD is measured at a specific temperature and specific period of time. BOD value is represented in the form of oxygen which is consumed per litre of the sample used for testing. The sample is tested before and after 5 days of incubation at 20 °C. The value describes the amount of organic material present in the contaminated or waste water. 

Thus, the correct answer is option B. 

Multiple choice biology human influences on the environment effects of water pollution effect of water pollution water pollution and its control

At DO below $4$ mg/$l$, water at normal temperature is considered as

  1. Heavily polluted

  2. Moderately polluted

  3. Little polluted

  4. Nearly pure
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Dissolved oxygen (DO) refers to the amount of oxygen dissolved in the water. It depends on the following factors:

1. Temperature- colder the temperature, more will be the DO.
2. Pressure- greater the pressure, more will be the DO.
3. Salinity- lower the salinity, more will be the DO.
The levels of DO below 5mg/l is considered to be hazardous to the aquatic lives. At normal temperature, any water body showing less DO than 5mg/l will be highly polluted.
Hence, the correct answer is 'Heavily Polluted'