The Electronic configuration of Cr and Cu are given below ⇒

1. Cr = 24 = 1s² 2s² 2p⁶ 3s² 4p⁶ 4s¹ 3d⁵

2. Cu = 29 = 1s² 2s² 2p⁶ 3s² 4p⁶ 4s¹ 3d¹⁰

These electronic configuration are exceptional because electrons entered in 3-d orbitals without filling the 4s orbitals complete.

Reason for the Exceptions ⇒ It is said that d orbitals can be stable if it is half filled or full filled.

Thus, In the given case, electrons reaches near the half filled and full filled thus due to the attraction one electrons from the s orbitals came in d orbitals.

Electronic configuration of Chromium, with atomic number 24=1s²2s²2p⁶3s²3p⁶4s¹3d⁵.

Electronic configuration of Copper, with atomic number 29=1s²2s²2p⁶3s²3p⁶4s¹3d¹⁰.

Distillation is the process of obtaining a pure liquid from solution.

The vapours of the liquid are cooled to get pure liquid. 

Distillation of water involves the boiling of water and the vapours form are condensed in condenser.

Condensation of water vapours gives pure water.

Free rotation around a bond is possible when the bond is formed by linear overlap.  Hence  there is free rotation around a sigma bond. There is no free rotation around a bond formed by parallel overlap.  Thus, there is no free rotation around a pi-bond.

Molecular orbitals of nitrogen and oxygen is as below:
 Nitrogen molecule has 14 electrons. So the electron distributions in molecular orbital are as below
 N₂ = σ1s2 σ*1s2   σ2s2 σ*2s2  σ2px2   π(2py22pz2)    
 
Bond order = (No. of electrons in bonding orbitals - No. of electrons in bonding orbitals)/2
                    =(10-4)/2 = 3
 Oxygen molecule has 16 electrons. So the electron distributions in molecular orbital are as below
 
O₂ = σ1s2 σ*1s2   σ2s2 σ*2s2  σ2px2   π(2py22pz2)  π*(2py1 2pz1)
Bond order= (10-6)/2 = 2
 As bond order of nitrogen is more than that of oxygen, nitrogen is more stable than oxygen.

Resonance

It is given by Heisenberg.

He took a molecule of ozone. Its structure was represented as:

According to the structure, it is clearly seen that it has one double bond and another single bond. So, obviously the bond lengths will be different. For double bond between oxygen atoms, the bond length is 121pm and for single bond it is 148pm.

Resonance structures: Is defined as difference  between actual bond energy and energy of most stable resonating structures.

• Resonance averages the bond characteristics of a molecule as a whole.
• Resonance stabilizes the molecule because energy of the resonance hybrid is less than the energy of any canonical forms.

CCl₄ molecule has zero dipole moment although the c-cl bond are polar this is because the shape of the molecule is tetrahedral and this make it very symmetrical and the four polar bond cancel out each other. so they have zero dipole moment.

Be has electronic configuration 1S²,2S² and s orbital is completely filled and doesn't require any electron to complete its orbital.Hence, Be₂ doesn't exist at all.

According to Fajans rule....

The charge on the ion increases the covalent character also increases because.

a high charge containing cation can polarise the anion more easily

as in fecl3 the charge of fe is +3 and the charge of fe in FeCl₂ is +2

the charge of fe in FeCl₃ is more so fecl3 is more covalent

The presence of -OH group helps in formation of hydrogen bonding. This helps in solubility of ethanol in water.

(i)  Limited scope: Arrhenius concept is limited to aqueous medium only. It fails to explain the behaviour of acids and bases in a non-aqueous solvent like ammonia,sulphur dioxide,alcohol, etc.

(ii) According to Arrhenius, the acidic and basic properties are due to H⁺ and OH^–ions respectively. However, these ions do not exist as such that readily get hydrated and represented as H⁺ (aq) and OH^– (aq).

(iii) It fails to explain the acidic nature of CO₂, SO₂, SO₃, N₂O₅ which do not contain any hydrogen.

(iv) It fails to explain the basic nature of CaO, NH₃,Na₂CO₃ which do not contain any hydroxyl group.

Electronic configuration of Chromium, with atomic number 24=1s²2s²2p⁶3s²3p⁶4s¹3d⁵.

Electronic configuration of Copper, with atomic number 29=1s²2s²2p⁶3s²3p⁶4s¹3d¹⁰.

The distribution of electrons into different shells, sub shells and orbitals of an atom is called its electronic configuration.

The electronic configuration of any orbital can be represented as:  nl^x

n is the number of principal shell, l = symbol of the sub shell or orbital, x= number of electrons present in the orbital

4p¹ means that p- sub shell of the 4th main shell contain one electron.

As we know Germenium Ge has the ground state electron configuration of 1s², 2s², 2p⁶, 3s², 3p⁶, 4s², 3d¹⁰, 4p²

Now in the condition of GeX₂ the two electrons are removed from the p shell,

and in case of GeX₄ the more two electrons are removed from 4s shell because it has low energy than d shell and the rest configuration remains same .

Now according to the question GeX₄ is more stable because it does not have a full valence so it is unfilled valance so GeX₄ is more stable than GeX₂.

On the other hand,

in pbx2 , oxidation state of pb =+2  

and pbx4 , oxidation state of pb =+4  

we know ,

oxidation state of +2 is more stable than +4 . due to inert pair effect.

Boyle’s Law

• Boyle’s law was stated by Robert Boyle.
• It states that at constanttemperature, the pressure of a fixednumber of moles nof gasvaries inversely with its volume.

k₁ = Proportionality constant.

• It depends upon the amount and temperature of gas. It also depends upon the units in which p as well v are expressed.
• Let volume V₁ is occupied at pressure P₁ and temperature T₁.
• Again volume V₂ is occupied at pressure P₂ and temperature T₂. Mathematically, as per Boyle’s law:

P₁ V₁= P₂ V₂ = Constant

P_1/P₂  = V_2/V₁ 

The electrostatic force of attraction which holds the two oppositely charged ions together is called the ionic bond.

Ionic bond and factors affecting it

• It is formed by transfer of electrons.
• It is formed between metal and no metal.
• In it metal always loses electrons and non-metal always accepts electron.

During the formation of methane molecule the carbon atom undergoes sp3 hybridization in the excited state by mixing one 2s and three 2p orbitals to furnish four half filled sp³ hybrid orbitals which are oriented in tetrahedral symmetry in space around the carbon atom. Each of these sp³ hybrid orbitals forms a σsp³-s bond with one hydrogen atom. Thus carbon forms four σsp³-s bonds with four hydrogen atoms.Methane molecule is tetrahedral in shape with 109°28 bond angle.

Ionization Enthalpy of elements is the amount of energy that an isolated gaseous atom requires to lose an electron in its ground state. Losing of electrons results in the formation of cations.

2. Quantum numbers may be defined as a set of 4 numbers with the help of which we can get complete information about all the electrons in an atom ,ie. location ,energy ,the type of Orbital occupied, space and orientation of that orbital.

1. 

postulates of Bohr's model of an atom are:

1. In an atom, the electrons revolve around the nucleus in certain definite circular paths called orbits, or shells.

2. Each shell or orbit corresponds to a definite energy. Therefore, these circular orbits are also known as energy levels or energy shells.

3. The orbits or energy levels are characterized by an integer not, where, n can have values 1, 2, 3, 4……. The integer not (= 1, 2, 3…) is called the quantum number of respective orbit. The orbits are numbered as 1, 2, 3, 4………… etc., starting from the nucleus side. Thus, the orbit for which n=1 is the lowest energy level.

The orbits corresponding to n = 1,2,3,4…..etc., are also designated as K,L,M,N……….etc., shells. When the electron is in the lowest energy level, it is said to be in the ground state.

Since, electronics can be present only in these orbits, hence, these electrons can only have energies corresponding to these energy levels, i.e., electrons in an atom can have only certain permissible energies .

4. The electrons present in an atom can move from a lower energy level (Elower) to a level of higher energy (Ehigher) by absorbing the appropriate energy. Similarly, an electron can jump from a higher energy level (Ehigher) to a lower energy level (Elower) by losing the appropriate energy.

The energy absorbed or lost is equal to the difference between the energies of the two energy levels, i.e.,

ΔE= E (higher) - E (lower)

sp Hybridization

sp hybridization is observed when one s and one p orbital in the same main shell of an atom mix to form two new equivalent orbitals. The new orbitals formed are called sp hybridized orbitals. It forms linear molecules with an angle of 180°

• This type of hybridization involves the mixing of one ‘s’ orbital and one ‘p’ orbital of equal energy to give a new hybrid orbital known as a sp hybridized orbital.
• sp hybridization is also called diagonal hybridization.
• Each sp hybridized orbital has an equal amount of s and p character, i.e., 50% s and p character.

sp³ Hybridization

When one ‘s’ orbital and 3 ‘p’ orbitals belonging to the same shell of an atom mix together to form four new equivalent orbital, the type of hybridization is called a tetrahedral hybridization or sp³. The new orbitals formed are called sp³ hybrid orbitals.

• These are directed towards the four corners of a regular tetrahedron and make an angle of 109°28’ with one another.
•  The angle between the sp3 hybrid orbitals is 109.28⁰
• Each sp³ hybrid orbital has 25% s character and 75% p character.
• Example of sp³ hybridization: ethane (C₂H₆), methane.

An electrolyte is a substance that dissociates in water into charged particles called ions. Positively charged ions are called cations. Negatively charged ions are called anions. Simply, an electrolyte is a substance that can conduct an electric current when melted or dissolved in water.