Molar mass of H₂S0₄ = 98g mol^-l.

(i) When an apple is cut, it turns brown after some time. This is because of oxidation.
(ii) Resting of iron is a redox reaction.
(iii) Oxidation of carbohydrates, lipids etc., to CO₂ and H₂O produce energy in the living organisms.

Na₂[Fe(CN)₆]
This compound contains a cation and a complex anion [Fe(CN)₆]^-4
Let the oxidation number of Iron = x
Each cyanide ion has charge = - 1
The sum of the oxidation number of the metal ion and the charges carried'by negative ions should be equal to the charge as the ion.
They x - 6 = - 4 or x = + 2.
Hence, Fe is in +2, oxidation state in this compound.

C₆H₁₂O₆ (C in C₆H₁₂O₆)
Oxidation number of carbon = x
Oxidation number of hydrogen = + 1
Oxidation number of oxygen = - 2
6x + 12 - 12 = 0 (or) 6x = 0 (or) x = 0
In organic compounds containing carbon, oxygen and hydrogen, the oxidation number of carbon atom is determined by the formula.
Oxidation number 'C' atom = \(\frac{n_0\times 2-n_H}{n_C}\)
Where n_o = number of oxygen atoms
n_H = number of hydrogen atoms
n_c = number of carbon atoms.

S₂O₃^-2 (S in S₂O₃^-2)
Oxidation number of sulphur = x
Oxidation number of oxygen = - 2
2x + 3 (- 2)  \(\Rightarrow\) 2x - 6 = - 2 (or) 2x ~ 4 or x = +2
Hence, the oxidation number of sulphur is S₂O₃^-2 is + 2.

ASO₃^-2 (As in ASO₃^-2)
Oxidation number of arsenic = x
Oxidation number of oxygen = - 2
x + 3 (- 2) = - 3.
Hence, the oxidation number of arsenic in arsenic oxide ASO₃^-2 is + 3.

CIO₃^- (CI in CIO₃^-)
Oxidation number of chlorine = x
Oxidation number of oxygen = - 2
x + 3 (-2) = -1
x - 6 = -1 or
x = 5
The oxidation number of chlorine in CIO₃^- is + 5.

H₄P₂O₇ (Pin H₄P₂O₇)
Oxidation number of hydrogen  = + 1
Oxidation number of phosphorous = x
Oxidation number of oxygen   = - 2
4 + 2x - 14 = 0
2x - 12 = 0
x = + 6
Hence, the oxidation number of phosphorous in H₄P₂O₇ is + 6.

NO₃^- (N in NO₃^-)
Oxidation number of nitrogen = x
Oxidation number of oxygen = - 2
x + 3 (- 2) = - 1
x - 6 = -1
x = + 5
Hence, the oxidation number of nitrogen in NO₃^- is + 5.

Molar Mass of ferrous Sulphate = \(\begin{cases} atomic\ \ mass\ of\ Fe+atomic\ mass\ of\ s' \\ +4x\ atomic\ mass\ of\ O\ \end{cases}\)
= 56 + 32 + 4 x 16 = 152
In reactions, Fe⁺² ion is oxidised to Fe⁺³ ion Fe⁺² \(\rightarrow\) Fe⁺³ + e
equivalent mass = \(\frac { Molar\quad mass }{ no\quad of\quad involved } =\frac { 152 }{ 1 } =152g{ eq }^{ -1 }\)

molar mass of crystalline oxalic acid (H₂C₂O₄.2H₂o) = Molar Mass of ocalic acid + 2 x Molar mass of H₂o
= 90 + 2 x 18 = 126
Bascity = 2
\(\therefore\) \(\begin{matrix} W\ equivalent\ \ mass\ of \\ crystalline\ \ oxalic\ \ acid \end{matrix}\} =\frac { 126 }{ 2 } =63g\) eq^-1

Molar mass of oxalic acid (H₂C₂O₄) = 2 x 1 + 2 x 12 + 4 x 16 = 90
Basicity of oxalic acid = 2
Equivalent Mass = \(\frac { 90 }{ 2 } =45g\) eq^-1

Molar mass of HNO₃ = 1 + 14 + 3 x 16 = 63
Basicity of HNO₃ = 1
Equivalent mass of HNO₃ = \(\frac { 63 }{ 1 } =63g\) eq^-1

Molar Mass of HCl = 1 + 35.5 = 36.5 
Basicity of HCl = 1
\(\therefore\) equivalent mass of hcl = \(\frac { 36.5 }{ 1 } =36.5g\) eq^-1

Number of mole =\(Weight \ of \ the \ substance \ in \ g \over gram \ atomic \ mass (or) \ gram \ molecular \ mass \)

Actual mass of an oxygen atom = The atomic mass of an element in a.m.u x 1.66 x 10^-24 g
= 16 x 1.66 x 10^-24
= 2.656 x 1O^-23 g

The mass of an atom (10^-27 kg) is too small to be measured directly. They are measured with reference to a standard atom, Hence they are called as relative atomic masses.

(i) The compound is made up of two or more atoms of different elements in a definite ratio by weight.
(ii) The properties of a compound is different from those of their constituent elements.

In a homogeneous mixture, the composition of the constituents are uniform throughout whereas in a heterogeneous mixture, the composition is not uniform throughout.

(i) Matter can be classified as solids, liquids and gases based on their physical state.
(ii) Matter can also be classified into mixtures and pure substances based on chemical composition.

(iv) \({ K }\overset { +7 }{ \underset { \underset { 2\times { 3e }^{ - } }{ \downarrow } }{ M } } n{ O }_{ 4 }+{ H }_{ 2 }\overset { -1 }{ \underset { { 1e }^{ - } }{ \underset { \uparrow }{ C_{ 2 } } } } { O }_{ 4 }+{ H }_{ 2 }{ SO }_{ 4 }\longrightarrow { K }_{ 2 }{ SO }_{ 4 }+\overset { +2 }{ M } n{ SO }_{ 4 }+\overset { +4 }{ C } { O }_{ 2 }+{ H }_{ 2 }O\)
2KMnO₄ + 5H₂C2O₄ + H₂S0₄ \(\longrightarrow \) Mn0₂ + Na₂S0₄ + KOH
2KMnO₄+ 5H₂C₂O₄ + H₂S0₄ \(\longrightarrow \) K₂SO₄ + 2MnSO₄ + 10CO₂ + H₂O
2KMnO₄ + 5H₂C₂O₄ + 3H₂S0_{4 \(\longrightarrow \)}  K₂S0₄ + 2MnS0₄ + lOC0₂ + 8H₂0

(iii) \(\overset { 0 }{ \underset { \underset { 2e^{ - } }{ \downarrow } }{ Cu } } { O }_{ 7 }+H\overset { +5 }{ \underset { { 1e }^{ - } }{ \underset { \uparrow }{ N } } } { O }_{ 3 }\longrightarrow \overset { +2 }{ Cu } \left( { No }_{ 3 } \right) _{ 2 }+\overset { +4 }{ N } { O }_{ 2 }+{ H }_{ 2 }O\)
Cu +2HNO₃ \(\longrightarrow \)  Cu(NO₃)₂ + NO₂ + H₂O
Cu + 2HNO₃ + 2HNO₃ \(\longrightarrow \) Cu(NO₃)₂ + 2NO₂ + 2H₂O
Cu + 4HNO₃ \(\longrightarrow \) Cu (NO₃)₂ + 2No₂ + 2H₂O

 (ii) \({ K }\overset { +7 }{ \underset { \underset { 3e^{ - } }{ \uparrow } }{ M } } n{ O }_{ 4 }+{ Na }_{ 2 }\overset { +4 }{ \underset { { 2e }^{ - } }{ \underset { \downarrow }{ S } } } { O }_{ 3 }\longrightarrow \overset { +4 }{ M } { nO }_{ 2 }+{ Na }_{ 2 }\overset { +6 }{ s } { O }_{ 4 }+KOH\)
\(\Rightarrow\) 2KMnO₄ + 3Na₂SO₃ \(\longrightarrow \)   MnO₂ + Na₂SO₄ + KOH
\(\Rightarrow\) 2KMnO₄ + 3Na₂SO₃ \(\longrightarrow \)  2MnO₂ + 3Na₂SO₄ + KOH
\(\Rightarrow\) 2KMNO₄ + 3NaSO₃ + H₂O \(\longrightarrow \) 2MnO₂ + ₃Na₂SO₄ +2KOH

Mol.mass = 2(H) + 1(S) + 4(0)
= 2(1) + 1(32) + 4(16)
= 2 + 32 + 64 = 98

Mol.mass = 3(H) + 1(B) + 3(0)
= 3(1) + 1(11) + 3(16)
= 3 + 11 + 48 = 62

Mol.mass = 3(C) + 6(H) + 1(0)
= 3(12) + 6(1) + 1(16)
= 36 + 6 + 16 = 58

\(\overset { o }{ Z } n\longrightarrow { Z }n^{ 2+ }\)
\(\overset { +5 }{ N } { O }_{ 3 }^{ - }\longrightarrow \overset { 2+ }{ NO } \)
(1) \(\Rightarrow \) Zn \(\rightarrow\) Zn²⁺ +2e^-                                  .....(3)
(2) \(\Rightarrow \) \({ NO }_{ 3 }^{ - }+{ 3e }^{ - }+{ 4H }^{ + }\longrightarrow NO+{ 2H }_{ 2 }O\)......(4)

half reaction \(\Rightarrow \) \({ S }_{ 2 }{ O }_{ 3 }^{ 2- }\longrightarrow { S }_{ 4 }{ O }_{ 6 }^{ 2- }\)
\({ I }_{ 2 }\longrightarrow { I }^{ - }\)
 

\(\overset { +3 }{ C } _{ 2 }{ O }_{ 4 }^{ 2- }\longrightarrow \overset { +4 }{ C } { O }_{ 2 }\)
\(\overset { +6 }{ Cr } _{ 2 }{ O }_{ 7 }^{ 2- }\longrightarrow { Cr }^{ 3+ }\)
(1)  \(\Rightarrow \) \({ C }_{ 2 }{ O }_{ 4 }^{ 2- }\longrightarrow { 2CO }_{ 2 }+{ 2e }^{ - }\)
\({ Cr }_{ 2 }{ O }_{ 7 }^{ 2- }\longrightarrow { 2Cr }^{ 3+ }+{ 7H }^{ 2 }O\)