Question 1

Assign oxidation number to the underlined elements in each of the following species:

(a) NaH_{2}PO_{4}

(b) NaHSO_{4}

(c) H_{4}P_{2}O_{7}

(d) K_{2}MnO_{4}

(e) CaO_{2}

(f) NaBH_{4}

(g) H_{2}S_{2}O_{7}

(h) KAl(SO_{4})_{2}.12 H_{2}O

Answer

(a) NaH_{2}PO_{4}

Let's assume oxidation number of P is x.

We know that,

Oxidation number of Na = +1

Oxidation number of H = +1

Oxidation number of O = -2

Then we have

1(+1) + 2(+1) + 1 (x) + 4(-2) = 0

⇒ 1 + 2 + x - 8 = 0

⇒ x - 5 = 0

⇒ x = + 5

Hence, oxidation number of P is +5

(b) NaHSO_{4}

Let's assume oxidation number of S is x.

Oxidation number of Na = +1

Oxidation number of H = +1

Oxidation number of O = -2

Then we have:

1(+1) + 1(+1) + 1 (x) + 4(-2) = 0

⇒ 1 + 1 + x - 8 = 0

⇒ x-6 = 0

⇒ x = +6

Hence, oxidation number of S is +6

(c) H_{4}P_{2}O_{7}

Let's assume oxidation number of P is x.

Oxidation number of H = +1

Oxidation number of O = -2

Then we have:

4(+1) + 2(x) + 7 (-2) = 0

⇒ 4 + 2x - 14 = 0

⇒ 2x - 10 = 0

⇒ 2x = +10

⇒ x = +5

Hence, Oxidation number of P is +5

(d) K_{2}MnO_{4}

Let's assume oxidation number of Mn is x.

Oxidation number of K = +1

Oxidation number of O = -2

Then we have:

2(+1) + 1(x) + 4 (-2) = 0

⇒ 2 + x - 8 = 0

⇒ x - 6 = 0

⇒ x = +6

Hence, Oxidation number of Mn is +6

(e) CaO_{2}

Let's assume oxidation number of O is x.

Oxidation number of Ca = +2

Then we have:

1(+2) + 2(x) = 0

⇒ 2 + 2x = 0

⇒ 2x = -2

⇒ x = -1

Hence, Oxidation number of O is -1

(f) NaBH_{4}

Let's assume oxidation number of B is x.

Oxidation number of Na = +1

Oxidation number of H = -1

Then we have:

1(+1) + 1(x) + 4(-1) = 0

⇒ 1 + x -4 = 0

⇒ x - 3 = 0

⇒ x = +3

Hence, Oxidation number of B is +3.

(g) H_{2}S_{2}O_{7}

Let's assume oxidation number of S is x.

Oxidation number of O = -2

Oxidation number of H = +1

Then we have:

2(+1) + 2(x) + 7(-2) = 0

⇒ 2 + 2x - 14 = 0

⇒ 2x - 12 = 0

⇒ x = +6

Hence, Oxidation number of S is +6.

(h) KAl(SO_{4})_{2}.12 H_{2}O

Let's assume oxidation number of S is x.

Oxidation number of K = +1

Oxidation number of Al = +3

Oxidation number of O = -2

Oxidation number of H = +1

Then we have:

1(+1) + 1 (+3) + 2(x) + 8(-2) + 24(+1) + 12 (-2) = 0

⇒ 1 + 3 + 2x -16 +24 -24 = 0

⇒ 2x - 12 = 0

⇒ 2x = +12

⇒ x = +6

Hence, Oxidation number of S is +6.

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Calculate the amount of carbon dioxide that could be produced when

(i) 1 mole of carbon is burnt in air.

(ii) 1 mole of carbon is burnt in 16 g of dioxygen.

(iii) 2 moles of carbon are burnt in 16 g of dioxygen.

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(a) MnO

_{4 }^{– }(aq) + I^{ – }(aq) → MnO_{2 (s)}+ I_{2(s)}(in basic medium)(b) MnO

_{4}^{–}(aq) + SO_{2 (g) }→ Mn^{2+}(aq) + HSO_{4}^{–}(aq) (in acidic solution)(c) H

_{2}O_{2 (aq)}+ Fe^{2+ }(aq) → Fe^{3+}(aq) + H_{2}O (l) (in acidic solution)(d) Cr

_{2}O_{7}^{2–}+ SO_{2(g)}→ Cr^{3+}_{(aq)}+ SO_{4}^{2– }(aq) (in acidic solution) - Q:-
In a process, 701 J of heat is absorbed by a system and 394 J ofwork is done by the system. What is the change in internal energy for the process?

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In a reaction A + B2 → AB2 Identify the limiting reagent, if any, in the following reaction mixtures.

(i) 300 atoms of A + 200 molecules of B

(ii) 2 mol A + 3 mol B

(iii) 100 atoms of A + 100 molecules of B

(iv) 5 mol A + 2.5 mol B

(v) 2.5 mol A + 5 mol B

- Q:-
At 0°C, the density of a certain oxide of a gas at 2 bar is same as that of dinitrogen at 5 bar. What is the molecular mass of the oxide?

- Q:-
Which one of the following will have largest number of atoms?

(i) 1 g Au (s)

(ii) 1 g Na (s)

(iii) 1 g Li (s)

(iv) 1 g of Cl2(g)

- Q:-
Density of a gas is found to be 5.46 g/dm

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- Q:-
At 0°C, the density of a certain oxide of a gas at 2 bar is same as that of dinitrogen at 5 bar. What is the molecular mass of the oxide?

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HNO

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^{–31}kg. If its K.E. is 3.0 × 10^{–25}J, calculate its wavelength. - Q:-
Pressure of 1 g of an ideal gas A at 27 °C is found to be 2 bar. When 2 g of another ideal gas B is introduced in the same flask at same temperature the pressure becomes 3 bar. Find a relationship between their molecular masses.

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What is meant by the term bond order? Calculate the bond order of: N

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For the reaction at 298 K,

2A + B → C

ΔH = 400 kJ mol

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- Q:-
Discuss the general characteristics and gradation in properties of alkaline earth metals.

- Q:-
Consider the elements:

Cs, Ne, I and F

(a) Identify the element that exhibits only negative oxidation state.

(b) Identify the element that exhibits only postive oxidation state.

(c) Identify the element that exhibits both positive and negative oxidation states.

(d) Identify the element which exhibits neither the negative nor does the positive oxidation state.

- Q:-
Calculate the amount of carbon dioxide that could be produced when

(i) 1 mole of carbon is burnt in air.

(ii) 1 mole of carbon is burnt in 16 g of dioxygen.

(iii) 2 moles of carbon are burnt in 16 g of dioxygen.

- Q:-
The Mn

^{3+}ion is unstable in solution and undergoes disproportionation to give Mn^{2+}, MnO^{2}, and H^{+}ion. Write a balanced ionic equation for the reaction.

Linju
2019-11-26 21:15:16

Gud to disclose all the answers .anyway thanks

- NCERT Chapter