Chemistry · Physics

Thermodynamics and Chemical Kinetics

1,092 Questions

Thermodynamics and chemical kinetics are crucial branches of physical chemistry. This area focuses on energy transformations, reaction rates, equilibrium constants, and catalysts. These topics carry significant weight in competitive science and engineering examinations.

Enthalpy and energyChemical equilibriumEntropy conceptsReaction kinetics and catalysts

Thermodynamics and Chemical Kinetics Questions

Multiple choice biology chemical coordination and integration mechanism of hormone action coordination in human beings- chemical control endocrine system in humans

Negative feedback inhibition .......... the mechanism to reverse the changes.

  1. Activates

  2. Inactivates

  3. Remove

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • A feedback mechanism for multistep reactions is a biological occurrence wherein the output of a system amplifies the system (positive feedback) or inhibits the system (negative feedback).
  • For example, Release of estrogen from the ovaries stimulates the secretion of GnRH from Hypothalamus which in turn stimulates the secretion of LH from anterior pituitary.when the levels of LH reaches above the normal levels in the blood it stimulates the release of progesterone from corpus luteum which causes the inhibition of the release of GnRH from the hypothalamus which in turn leads to inhibition of release of LH(product) from anterior pituitary and prevents the accumulation of LH(product)in blood. Hence negative feedback.
  • Hence Negative feedback inhibition activates the mechanism to reverse the changes.
  • So, the correct answer is 'Activates'.
Multiple choice physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

Identify the energy changes in the following cases
$A$: A car moving up a hill.
$B$: Photographic film is exposed to sun-light.

  1. In $'A'$ mechanical energy in moving car is converted to kinetic energy and in $'B'$ potential energy is converted to chemical energy.
  2. In $'A'$ potential energy in moving car is converted to kinetic energy and in $'B'$ chemical energy is converted to light energy.
  3. In $'A'$ kinetic energy in moving car is converted to potential energy and in $'B'$ potential energy is converted to light energy.
  4. In $'A'$ kinetic energy in moving car is converted to potential energy and in $'B'$ light energy is converted to chemical energy.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$A$: A car moving up a hill.
Moving car has kinetic energy, kinetic energy gets converted to potential energy as it gains height $(h)$.
And potential energy $=mgh$
$B$: Photographic film is exposed to sun -light.
When photographic film is exposed to Sun the silver bromide present in it decomposes, such that the film cannot be developed, here the light energy changes to chemical energy.

Multiple choice physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

What are the various energy transformations that occur when you are riding a bicycle ?

  1. Muscular energy to kinetic and heat energy

  2. Mechanical energy to chemical and light energy

  3. Chemical energy to Internal energy

  4. Rotational energy to muscular energy
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

While riding a bicycle,the muscular energy of the rider gets transferred to heat energy and kinetic energy of the bicycle.Heat energy heats the rider's body.Kinetic energy provides a velocity to the bicycle to move in rotation.The transformation can be shown as:
Muscular energy$=$kinetic energy+heat energy
During transformation,the total energy remains conserved.

Multiple choice physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

Burning of a meteorite in the earth's atmosphere is an example of change of :

  1. heat energy into kinetic energy

  2. kinetic energy into heat energy

  3. kinetic energy into potential energy

  4. potential energy into heat energy
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A meteorite has both potential and kinetic energy before entering earth's atmosphere. As it enters and fall towards the surface of earth, frictional heating occurs which is caused by collision with the molecules in the atmosphere which reduces its velocity. Hence the kinetic energy decreases, which is converted into heat energy. Potential energy is continuously decreasing being converted to kinetic energy.

Multiple choice physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

What are the various energy transformations that occur when you are riding bicycle?

  1. Muscular $\rightarrow$ Kinetic $\rightarrow$ Heat
  2. Potential $\rightarrow$ Kinetic $\rightarrow$ Heat
  3. Kinetic $\rightarrow$ Heat $\rightarrow$ Sound

  4. None
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

While paddling a bicycle muscular energy converted to kinetic energy as the bicycle moves.Rotation of wheel create friction causing loss of kinetic energy in the form of heat.

Multiple choice physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

In case of explosion of a bomb which of the following does not change?

  1. Chemical energy

  2. Total energy

  3. Kinetic energy

  4. Mechanical energy
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The chemical energy possessed by the bomb after explosion converts into heat energy, sound energy, light energy i.e. into different forms of energy but remains conserved. Hence, total energy of bomb does not change, but kinetic and mechanical energy changes.

Multiple choice movement in plants living world of plants - plant physiology biology

When spontaneous process occurs then free energy of a system _______________.

  1. Decreases

  2. Increases

  3. Remains same

  4. Either can decreases or increase
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

According to the second law of thermodynamics, spontaneous processes in a system at constant temperature and pressure occur with a decrease in Gibbs free energy.

Multiple choice evs how to save fuel define fossil fuels conservation of fuels reason for finishing of materials (resources) fuel and conservation

Energy can neither be created nor be destroyed, but it can be changed from one form to another. This law is known as:

  1. potential energy

  2. kinetic energy

  3. conservation principle

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

The law of conservation of energy states that the total energy of an isolated system remains constant, it is said to be conserved over time. This law means that energy can neither be created nor destroyed; rather, it can only be transformed from one form to another.

For instance, chemical energy is converted to kinetic energy when a stick of dynamite explodes. If one adds up all the forms of energy that were released in the explosion, such as the kinetic energy of the pieces, as well as heat and sound, one will get the exact decrease of chemical energy in the combustion of the dynamite.
 Classically, conservation of energy was distinct from conservation of mass; however, special relativity showed that mass could be converted to energy and vice versa by E = mc2, and science now takes the view that mass–energy is conserved.

Multiple choice chemistry chemistry of non-metals oxides of elements simple oxides oxygen

In view of the signs of $\Delta _{r}G^{0}$ for the following reactions :
$PbO _{2} +Pb \rightarrow 2PbO, \Delta _ {r}..G..^{0},0$
$SnO _{2} +Sn \rightarrow 2SnO, \Delta _ {r}..G..^{0},0$

  1. For lead +2, for tin +2

  2. For lead +4, for tin +4

  3. For lead +2, for tin +4

  4. For lead +4, for tin +2
Reveal answer Fill a bubble to check yourself
C Correct answer
Multiple choice chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

An isolated system is one which neither shows an exchange of _nor _with surroundings.

  1. heat, mass

  2. heat, temperature

  3. temperature, mass

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Heat, mass

In physical science, an isolated system is either 

(1) a thermodynamic system which is completely enclosed by walls through which can pass neither matter nor energy, though they can move around inside it; or 

(2) a physical system so far removed from others that it does not interact with them.

Hence, option A is correct.