Chemistry · Science General

States of Matter

2,682 Questions

States of matter questions explore physical changes, evaporation, phase transitions, and the properties of liquids and gases. Topics cover density, cryosurgery, heavy water, and electrolytes. This foundational chemistry topic frequently appears in general science sections of SSC and railway exams.

Phase change mechanismsEvaporation and temperature effectsProperties of liquidsPhysical versus chemical changesElectrolytes and heavy water

States of Matter Questions

Multiple choice physics heat engine: second law of thermodynamics second law of thermodynamics the second law of thermodynamics second law of thermodynamic

When water freezes, its molecules take on a more structured order. Why doesn't this contradict the Second Law of Thermodynamics? 

  1. Because the density of the water is decreasing

  2. Because the water is gaining entropy as it goes from liquid to solid state

  3. Because the waters internal energy is decreasing

  4. Because the surroundings are losing entropy

  5. Because the surroundings are gaining entropy
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

The Second Law of Thermodynamics tells us that the total amount of disorder, or entropy, in the universe is increasing. The entropy in a particular system can decrease, as with water molecules when they turn to ice, but only if the entropy in the surroundings of that system increases to an equal or greater extent. The Second Law of Thermodynamics holds, but only because the surroundings are gaining entropy, so the correct answer is E . Answer D refers to the key part of the answer, but gives the wrong information about the change in entropy of the surroundings. 
Answer C is not correct. This is an explanation for why the water does not lose heat when it freezes: it is, in fact, losing internal energy. This is an instance of the First Law of Thermodynamics, which states that the change in a systems internal energy is equal to the value of the heat transfer in the system minus the work done by the system. 

Multiple choice physics heat engine: second law of thermodynamics second law of thermodynamics the second law of thermodynamics second law of thermodynamic

For the conversion of liquid into a solid :

  1. orderliness decreases and entropy decreases

  2. orderliness increases and entropy increases

  3. both are not related

  4. orderliness increases and entropy decreases
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Entropy is related to the degree of order in the structure of a system and the second law of thermodynamics means that the system always changes from a more ordered state to a less ordered state in any isolated system.


In the solid phase, the molecules are arranged in a very orderly array. Each atom has a definite equilibrium location in the regular array of atoms and it can only move around with small displacements from its equilibrium position. In the gas phase, the molecules are far apart from each other and move around almost independently from each other in random fashion. In the liquid phase the situation is intermediate, being neither as orderly as in the solid nor as random as in the gas.

Therefore, in the phase transition from liquid into a solid, the $orderliness$ of the molecules $increases$. As the Entropy is a quantity to measure the order of a system. The $entropy$ of a system $decreases$ when the system undergoes a phase transition from liquid to solid.

Hence, $orderliness$ $increases$ $and$ $entropy$ $decreases.$
Therefore, the correct option is $'D'.$

Multiple choice physics heat engine: second law of thermodynamics second law of thermodynamics the second law of thermodynamics second law of thermodynamic

During the phase change, when water freezes, its converted to ice in which molecules is in more structured order. Why doesn't this contradict the Second Law of Thermodynamics?

  1. Because the density of the water is decreasing

  2. Because the water is gaining entropy as it goes from liquid to solid state

  3. Because the water's internal energy is decreasing

  4. Because the surroundings are losing entropy

  5. Because the surroundings are gaining entropy
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

The heat energy released during the freezing of water goes to the surrounding which increases the entropy of the surrounding. Thus although the entropy of the water decreases, the entropy of the surrounding increases such that the net entropy of system (water) and surrounding is greater than zero which does not violate the Second Law.

Hence option E is correct.

Multiple choice chemistry materials we use soap and detergents soap soap and detergent

Soaps are water soluble while detergents are water insoluble.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Soaps are water-soluble sodium or potassium salts of fatty acids. Soaps are made from fats and oils, or their fatty acids, by treating them chemically with a strong alkali.
A detergent is a surfactant, usually alkylbenzenesulfonates , a family of compounds that are similar to soap but are more soluble in hard water, because the polar sulfonate (of detergents) is less likely than the polar carboxyl (of soap) to bind to calcium and other ions found in hard water.Option B is correct.

Multiple choice chemistry materials we use soap and detergents soap soap and detergent

The soap molecule has a :

  1. hydrophilic head and a hydrophobic tail

  2. hydrophobic head and a hydrophilic tail

  3. hydrophobic head and a hydrophobic tail

  4. hydrophilic head and a hydrophilic tail
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
The basic structure of all soaps is essentially the same, consisting of a long hydrophobic (water-fearing) hydrocarbon chain tail and a hydrophilic (water-loving) anionic head.

Hence the correct option is A.
Multiple choice physics the kinetic model of matter force and kinetic theory change of states phase change

On increasing the external pressure , the boiling point of liquid 

  1. is raised

  2. is lowered

  3. remain unaffected

  4. uncertain
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
On increasing the external pressure, the boiling point of liquid is increased.
Boiling point is the temperature at which vapor pressure of the liquid equals to the external pressure.
V.P, of liquid is a function of temperature.
Now, if we increase the external pressure, a higher temperature would be required so that V.P. equals to external pressure.
Multiple choice physics the kinetic model of matter force and kinetic theory change of states phase change

A piece of ice at $0$ is put into a vessel containing water at $0$ . The ice will

  1. melt

  2. not melt

  3. slightly melt

  4. vanish in no time
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
A piece of ice at $0^oC$ is put into a vessel containing water at $0^oC$ ice will not melt.
The ice will not melt because no heat will transfer as there is no temperature difference. And without that heat transfer is impossible.