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Class 12th The d and f Block Elements

15. When a brown compound of manganese

(A) Is treated with HCl, it gives a gas

(B) The gas taken in excess, reacts with NH₃ to give an explosive compound

(C) Identify compounds A, B and C.

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Payal Gupta

Contributor-Level 10

15. The reactions are explained as:

MnO₂ + 4HCl → MnCl₂ + Cl₂ + 2H₂O

(A) (B)

3Cl₂ + 2NH₃ → NCl₃+ 3HCl

(excess) (C)

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Class 12th Application of Integrals

5. Find the area of the region bounded by the ellipse $\frac{x^{2}}{4} + \frac{y^{2}}{9} = 1$

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Vishal Baghel

Contributor-Level 10

Kindly go through the solution

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Class 12th General Principles and Isolation of Elements

35. In the extraction of aluminum by Hall-Heroult process, purified Al₂O₃ is mixed with CaF₂ to

(i) Lower the melting point of Al₂O₃.

(ii) Increase the conductivity of molten mixture.

(iii) Reduce Al³⁺into Al(s).

(iv) Acts as a catalyst.

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alok kumar singh

Contributor-Level 10

35. Option (i) and (ii)

In the extraction of alumina by Hall-Heroult's process, alumina is mixed with cryolite with the mixture of fluorspar \& fluoride that increases the conductivity of electrical and lowers the melting point of Al₂O₃ .

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Class 12th Application of Integrals

4. Find the area of the region bounded by the ellipse $\frac{x^{2}}{16} + \frac{y^{2}}{9} = 1$ .

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Vishal Baghel

Contributor-Level 10

Kindly go through the solution

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New answer posted

a year ago

Class 12th The d and f Block Elements

14. Out of Cu₂Cl₂ and CuCl₂, which is more stable and why?

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Payal Gupta

Contributor-Level 10

14. Higher enthalpy of hydration provides extra stability to Cu²⁺ oxidation state than +1 oxidation state.

Enthalpy of hydration is described as the amount of energy released on dilution of one mole of gaseous ions.

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a year ago

Class 12th Application of Integrals

3. Find the area of the region bounded by the curve x² = 4y ,y=2,y=4 and y-axis is the first quadrant.

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Vishal Baghel

Contributor-Level 10

Kindly go through the solution

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New answer posted

a year ago

Class 12th General Principles and Isolation of Elements

34. Which of the following options are correct?

(i) Cast iron is obtained by smelting pig iron with scrap iron and coke using hot air blast.

(ii) In extraction of silver, silver is extracted as a cationic complex.

(iii) Nickel is purified by zone refining.

(iv) Zr and Ti are purified by van Arkel method.

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alok kumar singh

Contributor-Level 10

34. Option (i) and (iv)

Pig iron is the iron obtained from the blast that has many impurities (Mn, P, Si, etc.) and approximately 4% carbon content. When it is re-melted or cast with the help of scrap iron, then it has less carbon content i.e. 3% as compared to pig iron.

The Zr andTi are purified by the help of Arkel Method that contain the following reaction:

Zr (s) + 2I₂ZrI₄ ( g) Zr Pure (s) + 2I₂

Ti + 2I₂ TiI₄ Ti + 2I₂

Here we obtain Zr and Ti as a pure form of solid when purified using the Arkel method.

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Class 12th Application of Integrals

2. Find the area of the region bounded by the curve y² = 9x and the lines x=2,x=4 and x-axis in the first quadrant.

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