The neutron magnetic moment is the magnetic moment of the neutron. It is of particular interest, as magnetic moments are created by the movement of electric charges. Since the neutron is a neutral particle, the magnetic moment is an indication of substructure, i.e. that the neutron is made of other, electrically charged particles (quarks).

The neutron magnetic moment is measured to be −1.9130427(5) μ_N, where μ_N is the nuclear magneton. In SI units, the neutron magnetic moment is approximately −9.6623640 × 10⁻²⁷ J/T

It's a transition where an electron jumps from one d orbital to another. Normally these are degenerate (the d orbitals have the same energy), but under some conditions, such as the presense of ligands, the degeneracy can be removed so that there is a specific energy (and therefore wavelength) associated with these transitions.

These sorts of transitions sometimes have energies located in the visible band, and it's one reason transition metal ions (and complex ions in particular) tend to be highly colored.

Equipotential Surfaces

An   equipotential surface is a surface on which the potential, or voltage, is constant. Electric field lines are always perpendicular to these surfaces, and the electric field points from surfaces of high potential to surfaces of low potential. Suppose, for example, that a set of surfaces has been chosen so that their voltages are 5 V, 4 V, 3 V, 2 V, etc.. Then since the voltage difference between neighboring sheets is constant ( V) we can estimate the magnitude of the electric field between surfaces by the formula 

where  is the perpendicular distance between neighboring surfaces. (This formula is really just an approximate version of the path-integral definition of the voltage difference given above.) Note that this means that the electric field is strong where the equipotential surfaces are close together and weak where they are far apart.

 It is because formation of ozone takes place by UV radiation at higher altitudes far above the surface of earth. Following is the mechanism:

Oxygen gas (two molecules of oxygen, or O₂) is present in the atmosphere. High energy UV light collides with the oxygen molecule, causing it to split into two oxygen atoms. These atoms are unstable, and they prefer being "bound" to something else. The free oxygen atoms then smash into other molecules of oxygen, forming ozone. What’s the overall reaction?

O_{1 (atom)} + O_{2 (oxygen gas)} -> O_{3 (ozone)}

The ozone is destroyed in the very process that protects us from UV rays emitted by the sun. When ozone (O₃) absorbs UV light, it will split the molecule into one free oxygen atom (O₁) and one molecule of oxygen gas (O₂).

O_{3 (ozone)} -> O_{1 (atom)} + O_{2 (oxygen gas)}

Ozone is valuable to us because of the way it is destroyed – it absorbs UV radiation in the process. Even low-energy radiation can split ozone. 
Now look at the ozone layers again and answer some questions.

Inertial mass

Inertial mass is the mass of an object measured by its resistance to acceleration.

To understand what the inertial mass of a body is, one begins with classical mechanics and Newton's Laws of Motion. Later on, we will see how our classical definition of mass must be altered if we take into consideration the theory of special relativity, which is more accurate than classical mechanics. However, the implications of special relativity will not change the meaning of "mass" in any essential way.

According to Newton's second law, we say that a body has a mass m if, at any instant of time, it obeys the equation of motion

,

where F is the force acting on the body and α is the acceleration of the body.^{[note 2]} For the moment, we will put aside the question of what "force acting on the body" actually means.

This equation illustrates how mass relates to the inertia of a body. Consider two objects with different masses. If we apply an identical force to each, the object with a bigger mass will experience a smaller acceleration, and the object with a smaller mass will experience a bigger acceleration. We might say that the larger mass exerts a greater "resistance" to changing its state of motion in response to the force.

However, this notion of applying "identical" forces to different objects brings us back to the fact that we have not really defined what a force is. We can sidestep this difficulty with the help of Newton's third law, which states that if one object exerts a force on a second object, it will experience an equal and opposite force. To be precise, suppose we have two objects A and B, with constant inertial masses m_X and m_Y. We isolate the two objects from all other physical influences, so that the only forces present are the force exerted on X by Y, which we denote F_XY, and the force exerted on Y by X, which we denote F_YX. Newton's second law states that

,

,

where α_X and α_Y are the accelerations of X and Y, respectively. Suppose that these accelerations are non-zero, so that the forces between the two objects are non-zero. This occurs, for example, if the two objects are in the process of colliding with one another. Newton's third law then states that

;

and thus

.

Note that our requirement that α_X be non-zero ensures that the fraction is well-defined.

This is, in principle, how we would measure the inertial mass of an object. We choose a "reference" object and define its mass m_Y as (say) 1 kilogram. Then we can measure the mass of any other object in the universe by colliding it with the reference object and measuring the accelerations.

 In physics, mass, more specifically inertial mass, can be defined as a quantitative measure of an object's resistance to the change of its speed. In addition to this, gravitational mass can be described as a measure of magnitude of the gravitational force which is

1) exerted by an object (active gravitational mass), or

2) experienced by an object (passive gravitational force)

Moment of Inertia

Moment of inertia is the name given to rotational inertia, the rotational analog of mass for linear motion. It appears in the relationships for the dynamics of rotational motion. The moment of inertia must be specified with respect to a chosen axis of rotation. For a point mass the moment of inertia is just the mass times the square of perpendicular distance to the rotation axis, I = mr². That point mass relationship becomes the basis for all other moments of inertia since any object can be built up from a collection of point masses.

  Sporulation: Molds like to reproduce through this method. A spore is basically a reproductive cell that can grow into a new cell through mitotic cell division. Spore are stored in special spore cases until they are ready to be released. If conditions are favorable, they will grow into new individual cells. Bread mold reproduce in this manner.

Asexual Reproduction

In many simple organisms, reproduction is not a very complicated thing. It generally involves only one organism. The resulting offspring often have the exact same genetic information as the parent. This type of reproduction in which one parent is involved in the production of an identical offspring is called asexual reproduction.

Asexual reproduction can take place in a variety of ways. They may include:

	Binary Fission: A situation in which the parent cell splits in half producing two identical cells.
	Fragmentation: This type of reproduction would most likely occur in molds, yeast, and mushrooms, all of which are part of the Fungi family of organisms. These organisms produce tiny filaments called Hyphae. These hyphae obtain food and nutrients from the body of other organisms in order to grow and fertilize. When a piece of hyphae breaks off and grows into a new individual, this is called fragmentation.
	Budding: When conditions are favorable. yeast cells can reproduce through budding. Once a copy of the genetic material is made, a bud begins to form outside the body of the yeast cell. It continues to grow larger until, eventually, it breaks away to form a new individual cell.
	Sporulation: Molds like to reproduce through this method. A spore is basically a reproductive cell that can grow into a new cell through mitotic cell division. Spore are stored in special spore cases until they are ready to be released. If conditions are favorable, they will grow into new individual cells. Bread mold reproduce in this manner.
	Regeneration: A form of asexual reproduction that take place in some invertebrates from the animal kingdom. These also produce offspring that are identical to parent. Planaria, a type of flat worm, reproduces itself by dividing in two and regenerating the missing parts. They also have the ability to regenerate injured body parts.

 Spontaneity and Randomness

Careful examination shows that in each of the processes E. g. melting of ice and evaporation of rain water, there is an increase in randomness or disorder of the system. The water molecules in ice are arranged in a highly organised crystal pattern which permits little movement. As the ice melts, the water molecules become disorganised and can move more freely.

The movement of molecules becomes free still when the water evaporates into space as now they can roam about throughout the entire atmosphere. In other words, it may be said that randomness of the water molecules increases as ice melts into water or water evaporates into vapour.

 Nature of driving force

For many years scientists believed that only exothermic changes resulting in a lowering of internal energy or enthalpy could occur spontaneously. But melting of ice is an endothermic process and yet occurs spontaneously. On a warm day, ice melts by itself. The evaporation of water is another example of spontaneous endothermic process.

Thus arose the need of finding another driving force that affects the spontaneity. This was known as the entropy change,  Also the increase in randomness favours a spontaneous change.

Criteria of Spontaneity

Some important criteria of spontaneous processes are as follows:

(i)     A spontaneous change is one way or unidirectional. For reverse change to occur, work has to be done.

(ii)     For a spontaneous change to occur, time is no factor. A spontaneous reaction may take place rapidly or very slowly.

(iii)    If the system is not in equilibrium state, a spontaneous change is inevitable. The change will continue till the system attains the state of equilibrium.

(iv)      Once a system is in equilibrium state, it does not undergo any further spontaneous change in state if left undisturbed. To take the system away from equilibrium, some external work must be done on the system.

A spontaneous change is accompanied by decrease of internal energy or enthalpy . It implises that not only such reactions will occur which are exothermic, but the melting of ice and evaporation of rain water are endothermic processes which proceed spontaneously.

Clearly, there is some other factor in addition to AH which governs spontaneity. It is the second law of thermodynamics which introduces the new factor which is called Entropy.

 The second law of thermodynamics states that, “Whenever a spontaneous process takes place, it is accompanied by an increase in the total energy of the universe”.

More specifically the term universe means the system and the surroundings, thus,

The second law as stated above tells us that when an irreversible spontaneous process occurs, the entropy of the system and the surrounding increases. In other words, when reversible process occurs, the entropy of the system remains constant. .

Since the entire universe is undergoing spontaneous change, the second law can not be most generally and concisely stated as the entropy of the system is constantly increasing.

(1)    Kelvin-Planck statement

“It is impossible to construct a heat engine which, operating in cycles, can perform work at expense of heat obtained from a single thermal reservoir”.

(2)    Planck statement

“It is impossible to construct a device which will work in a complete cycle and to convert heat into work without producing any change in the surroundings”.

(3)    Clausius statement

“It is impossible for a self active machine, unaided by any external agency, to transfer heat from a body at a low temperature to one at a higher temperature”.

(4)    Ludwig Boltzmann statement

According to this “Nature tends to pass from a less probable to more probable state”.

(5)    It is impossible to construct a heat engine (of) 100% thermal efficiency.

(6)    The Entropy of the universe increases in a spontaneous process and remains constant in an equilibrium process-

For a spontaneous process:

At equilibrium

Although the second law has been stated in a number of ways but all the statements ultimately are modifications of the same fundamental concept i.e. work can always be converted into heat but the conversion of heat into work does not take place under all conditions.

The entropy of a substance is real physical quantity and is a definite function of the state of the body like pressure, temperature, volume of internal energy.

It is difficult to form a tangible conception of this quantity because it can not be felt like temperature or pressure. We can, however, readily infer it from the following aspects:

1. Entropy and unavailable energy

The second law of thermodynamics tells us that whole amount of internal energy of any substance is not convertible into useful work. A portion of this energy which is used for doing useful work is called available energy. The remaining part of the energy which cannot be converted into useful work is called unavailable energy. Entropy is a measure of this unavailable energy. In fact, the entropy may be regarded as the unavailable energy per unit temperature.

I.e.

or, 

The concept of entropy is of great -value and it provides the information regarding structural changes accompanying a given process.

2.  Entropy and disorder

Entropy is a measure of the disorder or randomness in the system. When a gas expands into vacuum, water flows out of a reservoir, spontaneous chain reaction takes place, an increase in the disorder occurs and therefore entropy increases.

Similarly, when a substance is heated or cooled there is also a change in entropy.Thus increase in entropy implies a transition from on ordered to a less ordered state of affair.

3. Entropy and probability

Why is disorder favoured? This can be answered by considering an example, when a single coin is flipped, there is an equal chance that head or tail will show up. When two coins are flipped, there is a chance of two heads or two tails showing up but there are double chance of occurrence of one head and one tail. This shows that disorder is more frequent than order.

Changes in order are expressed quantitatively in terms of entropy change, . How are entropy and order in the system related? Since a disordered state is more probable for systems than of order(see figure), the entropy and thermodynamic probabilities are closely related.

Order and probality

Features of entropy:

(1)    It is an extensive properly and a state function

(2)    It’s value depends upon mass of substance present in the system

(3)    

(4)    At equilibrium 

(5)    For a cyclic process 

(6)    For natural process  i.e Increasing.

(7)    For a adiabatic process  zero

 For a reversible change at constant temperature the change in entropy is equal to heat absorbed or evolved divided by the constant temperature in Kelvin.

Thus,

The unit of entropy in . The value of AS is positive if heat is absorbed and negative if heat is evolved. The entropy change in melting a solid can be calculated if enthalpy of fusion  is known.

Similarly, the entropy change for vaporisation of a liquid into its vapour at its boiling point can be calculated if enthalpy of vapourisation  is known.

Similarly the entropy of sublimation is given as

It is important to note that, the entropy change for a reaction carried out reversibly is different from a reaction carried out irreversibly. In other words, for an irreversible spontaneous change,

For a reversible change,

Entropy changes for Ideal gases:

(A)   For change of state: (Initial to final)

(B)   For isothermal process:

(C)   For Isochoric process:

(D)   For Isobaric process:

Some examples of increase or decrease of entropy:

On stretching a rubber band the entropy decreases as the coiled macro molecule become un-coiled i.e. randomness in structure decreases.

 Increase of entropy losses:

On boiling an egg entropy increases as due to denaturation the helical structure of protein become more complicated and random coiled structure.

In a solution of  is very high due to extensive H-bonding.

Trouton’s rule: According to .it  of most of the liquids is  / mole K at normal B.P.

 In order to define this term, let us consider a process taking place isothermally and reversibly at constant pressure. There will be a volume change say . The maximum work obtained by it will not be amount of energy available for doing useful work. From the total amount of work, some part of the work is used to perform the mechanical work or pressure volume work of expansion or contraction against the atmospheric pressure. This work will be equal to .

Hence the whole of work given by the process will be made up of two parts:

(a)    The mechanical work of expansion or contraction.

(b)   The work other than mechanical work is known as the net work . The net work includes all other forms of work energy performed by the system on the surroundings which can be applied to useful work. Thus net work done can be given by

 …..(1)

According to first law of thermodynamics,

 

 ….(2)

 

Substituting the value of  from (1) in (2), we get

 

On integration, it gives

….(3)

Thus  is determined by the initial and the final states of the process and is equal to the decrease in (E — TS +PV). This combination of properties is called Gibb’s free energy and is represented by G.

I.e.

G = E – TS + PV

Or,  G = E + PV – TS

Or,  G = H – TS[ ]

This is known as Gibb’s Helmholtz equation.

The Gibb’s free energy is a better criterion for spontaneity over total entropy change because Gibb’s free energy considers only the entropy change of the system and not the surroundings. Thus we can write above equation as:

 

Where 

The following three values are possible for :

(i)     is positive: It means the reaction is non-Spontaneous.

(ii)    is negative: It means the reaction is spontaneous.

(iii)     is zero: It means the reaction is in equilibrium state.

The standard free energy change, ,(E.g. a gas is at 1 atm pressure and concentration of all reactants and products in solution is 1 M) is also related with equilibrium constant as:

 

Where all the terms have usual meaning.