(i) Aromatisation:
Alkanes with six to ten carbon atoms are converted into homologous of benzene at high temperature and in the presence of catalyst. This process is known as aromatization. It occurs by simultaneous cyclisation followed by dehydrogenation of alkanes n-Hexane passed over Cr₂O₃ supported on alumina at 873 K gives benzene.

(ii) Pyrolysis:
Pyrolysis is dened as the thermal decomposition of organic compound into smaller fragments in the absence of air through the application of heat. 'Pyro' means 'fire' and 'lysis' means 'separating'. Pyrolysis of alkanes also named as cracking.
In the absence of air, when alkane vapours are passed through red-hot metal it breaks down into simpler hydrocarbons.
1)                        CH₃-CH₂-CH₃
                                    \(\downarrow 773K\) 
\({ CH }_{ 3 }-CH={ CH }_{ 2 }+{ CH }_{ 2 }={ CH }_{ 2 }+{ H }_{ 2 }+{ CH }_{ 4 }\)
2) 2CH₃-CH₃ \(\overset { 773K }{ \longrightarrow } \) CH₂ = CH₂ + 2CH₄
The products depends upon the nature of alkane, temperature, pressure and presence or absence of catalyst. The ease of cracking in alkanes increases with increase in molecular weight and branching in alkanes. Cracking plays an, important role in petroleum industry.

Restricted rotation around C=N (oximes) gives rise· to geometrical isomerism in oximes. Here 'syn' and 'anti' are used instead of cis and trans respectively. In the syn isomer the H atom of a doubly bonded carbon and -OH group of doubly bonded nitrogen lie on the same side of the double bond, while in the anti isomer, they lie on the opposite side of the double bond. For Eg:

Pesticides are the chemicals that are used to kill or stop the growth of unwanted organisms. But these pesticides can affect the health of human beings. These are further classified as
a. Insecticides:
Insecticides like DDT ,BHC ,aldrin etc. can stay in soil for long period of time and are absorbed by soil . Th.y contaminate root crops like carrot, raddish, etc.
b. Fungicide :
Organo mercury compeunds are used as most common fungicide. They dissociate in soil to produce mercury which is highly toxic.
c. Herbicides :
Herbicides are the chemical compounds used to control unwanted plants. They are otherwise known as weed killers. Example sodium chlorate (NaClO₃) and sodium arsenite (Na₃ As O₃). Most of the herbicides are toxic to mammals.

Optical isomerism:
Compounds having same physical and chemical property but differ only in the rotation of plane of the polarized light are known as optical isomers and the phenomenon is known as optical isomerism.
Some organic compounds such as glucose have the ability to rotate the plane of the plane polarized light and they are said to be optically active compounds and this property of a compound is called optical activity. The optical isomer, which rotates the plane of
the plane polarised light to the right or in cloclauisl direction is said to be dextrorotary (dexter means right) denoted by the sign (+), whereas the compound which rotates to the left or anticloclanrise is said to be leavo rotatory (leanues mean left) denoted by sign(-).
Dextrorotatory compounds are represented as 'd' or by sign (+) and lavorotatory compounds are ( - ) represented as 'l' or by sign (-).
Enantiomerism and optical activity: An optically active substance may exist in two or more isomeric forms which have same physical and chemical properties but differ in terms of direction of rotation of plane polarized light, such optical isomers which rotate the plane of polarized light with equal angle but in opposite direction are known as enantiomers and the phenomenon is knovrrn as enantiomerism. Isomers which are non-super impossible mirror images of each other are called enantiomers.
conditions for enantiomerism or optical isomerism:
A carbon atom whose tetra vaiency is satisfied by four different substituents (atoms or groups) is called a symmetric carbon or chiral carbon. It is indicated by an asterisk as C*. A molecule Possessing chiral carbon atom and non-super impossible to its own mirror image is said to be a chiral molecule or asymmetric, and the pioperty is called chirality or dissymmetry.

The balanced equation for the formation of HCI is,
H₂(g) + CI₂(g) \(\rightarrow\) 2 HCI (g)
As per the stoichiometric equation, under given conditions,
To produce 2 moles of HCI, 1 mole of chlorine gas is required.
To produce 44.8 litres of HCI, 22.4 litres of chlorine gas are required.
\(\therefore\) To produce 11.2 litres of HCI,

= 5.6 litres of chlorine are required.

Molar Heat of Fusion: The molar heat of fusion is defined as "The change in enthalpy when one mole of a solid substance is converted into the liquid state at its melting point". For example heat of fusion of ice can be represented as
H₂O_(s) \(\overset { 273k }{ \rightarrow } \) H₂O(l) ΔH_fusion = + 5.98 KJ

(i) The number of electrons increases by the same number as the increase in the atomic number.
(ii) As the number of electrons increases, the electronic structure of the atom changes.
(iii) Electrons in the outermost shell of an atom (valence electrons) determine the chemical properties of the elements.

At a given temperature the volume occupied by a fixed mass of a gas is inversely proportional to its pressure.
\(V\alpha \frac { 1 }{ P }\) at constant T& n.
Mathematical form: P₁V₁ = P₂ V₂ = K

(i) V and VI, VI and VII form a pair of metamers. Metamers are compounds which differ in the number of carbon atoms.
(ii) Functional isomers are compounds having same molecular formula, but different functional group; 1 and V, I and VI, I and VII, II and V, II and VI, II and VII, III and V, III and VI, III and VII, IV and V, IV and VI and IV and VII are functional isomers.
(iii) I and II, III and IV, VI and VII are position isomers. Compound that possess same molecular formula, carbon skeleton but differ in the position of functional group are called position isomers.
(iv) Compounds having same molecular formula but different carbon skeleton are called chain isomers. I and II, I and IV, II and III, II and IV are chain isomers.
(vi) None of these compounds exhibit geometrical isomerism, because to get geometrical isomers, restricted rotation about C = C is mandatary.

Elimination reactions may proceed through two different mechanisms namely E₁ and E₂

(i) The rate of E₂ reaction depends on the concentration of alkyl halide and base Rate = k [alkyl halide] [base]
(ii) It is therefore, a second order reaction. Generally primary alkyl halide undergoes this reaction in the presence of alcoholic KOH. It is a one step process in which the abstraction of the proton from the . p carbon and expulsion of halide from the a carbon occur simultaneously. The mechanism is shown below.


(iii) Generally, tertiary alkyl halide which undergoes elimination reaction by this mechanism in the presence of alcoholic KOH. It follows first order kinetics. Let us. consider the following elimination reaction.
Step - 1: Heterolytic fission to yield a carbocation

Step - 2 Elimination of a proton from the \(\beta\)- carbon to produce an alkene.

(i) BOD and COD

(ii) Viable and non-viable particulate pollutants

\(\Delta T_f=0.093^oC=0.093K\)
m = ?
K_f = 1.86K Kg mol^-1
\(\Delta T_f=K_f.m\)
\(\therefore m={\Delta T_f\over K_f}\)
\(={0.093K\over 1.86\ K\ Kg\ mol^{-1}}\)
= 0.05 mol Kg^-1
= 0.05 m.

Given data:
[A] = [B] = [C]= [D] =1 M
K_c = 100
[D]_eq = ?
Solution:
Let x be the no moles of reactants reacted

\(K_c={[C][D]\over [A][B]}\)
\(100={(1+x)(1+x)\over (1-x)(1-x)}\)
\(\sqrt{100}=\sqrt{{(1+x)(1+x)\over (1-x)(1-x)}}\)
\(10={1+x\over 1-x}\)
10(1 - x) = 1 + x
10 - 10x - 1 - x = 0
9 - 11x = 0
11x = 9
\(x={9\over 11}=0.818\)
[D]eq = 1+x = 1 + 0.818 = 1.818M.

Empirical formula shows the ratio of number of atoms of different elements in one molecule of the compound.
Steps for finding the Empirical formula:
The percentage of the elements in the compound is determined by suitable methods and from the data collected; the empirical formula is determined by the following steps.
(i) Divide the percentage of each element by its atomic mass. This will give the relative, number of atoms of various elements present in the compound.
(ii) Divide the atom value obtained in the above step by the smallest of them so as to get a simple ratio of atoms of various elements.
(iii) Multiply the figures so obtained, by a suitable integer if necessary in order to obtain whole number ratio.
(iv) Finally write down the symbols of the various elements side by side and put. the above numbers as the subscripts to the lower right hand of each symbol. This will represent the empirical formula of the compound,
(v) Percentage of Oxygen = 100 - Sum of the percentage masses of all the given elements.

(i) Intermolecular hydrogen bonds occur between two separate molecules. They can occur between any numbersof like or unlike molecules as long as hydrogen donors and acceptorsare present in positions which enable the hydrogen bonding interactions. For example, intermolecular hydrogen bonds can occur between ammonia molecule themselves or between.water molecules themselves or between ammonia and water.
(ii) Intramolecular hydrogen bonds are those which occur within a single molecule.

(i) no. of electrons: 35 (given)
no. of protons : 35
(ii) Electronic configuration
1s² 2S² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁵
(iii) Last electron:

4P_x        4P_y     4p_z
last electron present in 4P_y orbital y
n = 4, l = 1 m₁ = either + 1 or -1 and s = -1/2

Volume of oxygen V₁ = 2.5 L
at a pressure P₁ = 5.0 atm
At pressure P₂ = 1.01 atm
Volume of oxygen V₂ = ?
According to Boyle's law
P₁ V₁ = P₂ V₂
5 \(\times\) 25 = V₂ \(\times\) 1.01
\({ V }_{ 2 }=\frac { 12.5 }{ 1.01 } =12.37\quad L\)
Volume of oxygen at a pressure of 1.01 atm
= 12.37 l

T_sys=77°C = (77 + 273) = 350 K
T_surr=33°C = (33 + 273) = 306 K
q=245 J
ΔS_sys=\(\frac{q}{T_{sys}}=\frac{-245}{350}=-0.7JK^{-1}\)
ΔS_surr=\(\frac{q}{T_{sys}}=\frac{+245}{350}=0.8JK^{-1}\)
ΔS_univ=ΔS_sys+ΔS_surr
ΔS_univ=-0.7 JK^-1+ 0.8 JK^-1
ΔS_univ=0.1 JK^-1.

(i) Alkaline earth metal (A) belonging to 3rd period is magnesium.
(ii) So A is Magnesium. Magnesium reacts with oxygen and nitrogen as follows.
\(2Mg+O_2⟶\underset{(B)}{2MgO}\)
\(3Mg+N_2⟶\underset{(C)}{Mg_3N_2}\)
So B is Magnesium oxide and C is magnesium nitride.
(iii) Magnesium undergoes metal displacement reaction with AgNO₃ as follow to give D as follows :
\(Mg+2AgNO_3⟶\underset{D}{Mg(NO_3)_2}+2Ag\)
So D is Magnesium nitrate.
Result  :

Screening effect: The repulsive force between the inner shell electrons and the valence electrons leads to a decrease in the electrostatic attractive forces acting on the valence electrons by the nucleus. Thus, the inner shell electrons act as a shield between the nucleus and the valence electrons. This effect is called shielding effect.
Pauling's scale: Pauling, he assigned arbitrary value of electronegativities for hydrogen and fluorine as 2.2 and 4.0 respectively. Based on this the electronegativity values for other elements can be calculated using the following expression.
\(({ X }_{ A }-{ X }_{ B })=0.182\sqrt { E_{ AB } } -({ E }_{ AA }*{ E }_{ BB })^{ 1/2 }\)
Where E_AB' EAA and E_BB are the bond dissociation energies of AB, A₂ and B₂ molecules respectively. The electronegativity of any given element is not a constant and its value depends on the element to which it is covalently bound. The electronegativity values play an important role in predicting the nature of the bond.

(a) Both assertion and reason are correct and the reason is the correct explanation for an assertion

The anion of Na₂O₂ isO^2-₂ (peroxide ion).
No. of electrons in O^2-₂: 8 + 8 + 2 = 18 e^-
Electronic configuration: \((\sigma_{1s})^2 (\sigma^*_{1s})^2(\sigma^s_{2})^2(\sigma^{s*}_{2})\)\((\sigma_2p_z)^2(\pi_2p_x)^2(\pi_2p_y)^2(\pi^*_2p_x)^2(\pi^*_2p_y)^2\)
Bond order: \({1\over2}(N_b-N_a)={1\over2}(10-8)=1\)
Magnetic Nature: Has no unpaired electrons. Hence diamagnetic.

The Chlorination of methane is carried out by free radical mechanism. The initiation step to form free radical needs high energy which is supplied by light energy.
\(\mathrm{Cl}-\mathrm{Cl} \stackrel{h \nu}{\longrightarrow} 2 \mathrm{Cl}\)
So this reaction is not possible in dark.

CaCO_3(s) \(\rightarrow\) CaO_(s) + CO_(g)
100g                       22.4L
100 g of CaCO₃ produces 22.4 L of CO₂.
\(\therefore\) 25 g of CaCO₃ will purchase  = \(\frac { 22.4 }{ 100 } \times 25\)
= 5.6 L of CO₂.

This law states that "The physical and chemical properties of elements are a periodic function of their atomic weights."

Isobars are the plot of volume Vs temperature at constant pressure and isochores are plot of pressure verses temperature at constant volume.

Heavy water is toxic when taken in large quantities. Heavy water is not radioactive. The deuterium in it is stable; it does not decay. Nobody will be in danger at all from radiation. It is heavier than plain water. D₂O performs little different from H₂O in chemical reactions. One has to drink a lot of D₂O to kill him.