Ncert Solutions Chemistry Class 11th

Water sample is called cleanest on the basis of which one of the BOD values given below:

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BOD is biological oxygen demand which represents the amount of oxygen required to degrade organic matter in water.

Higher the BOD more polluted the water is

So; here water sample with BOD = 3 ppm is the cleanest

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7 months ago

Choose the correct order of density of the alkali meals:

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Density of metal a very specific and depends upon many factors.

Li -> 0.53 gm/cm³

Na -> 0.97 gm/cm³

K -> 0.86 gm/cm³

Rb ->1.53 gm/cm³

Cs -> 1.90 gm/cm³

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7 months ago

The measured BOD values for four different water sample (A-D) are as follows

A = 3 ppm; B = 18 ppm: C = 21 ppm; D = 4 ppm.

The water samples which can be called as highly polluted with organic wastes, are

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Highly polluted water has higher value of BOD ≥17 ppm

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7 months ago

Which one of the following is an example of disproportionation reaction?

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Disproportionation reaction is

$\overset{+ 6}{M g} O_{4}^{- -} + 4 H^{+} \to 2 \overset{+ 7}{M n} O_{4}^{-} + \overset{+ 4}{M n} O_{2} + 2 H_{2} O$

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The oxide which contains an odd electron at the nitrogen atom is

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Kindly consider the below image

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Boiling of hard water is helpful in removing the temporary hardness by converting calcium hydrogen carbonate and magnesium hydrogen carbonate to

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During removal of temporary hardness of water.

$\begin{array}{l} M g {(H C O_{3})}_{2} \overset{B o i l}{\to} M g {(O H)}_{2} + 2 C O_{2} ↑ \\ C a {(H C O_{3})}_{2} \overset{B o i l}{\to} C a C O_{3} + H_{2} O + C O_{2} \end{array}$

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7 months ago

Identify the correct statement from B₂H₆ from those given below :

(A) In B₂H₆, all B-H bonds are equivalent

(B) In B₂H₆, there are four 3-centre 2- electron bonds

(C) B₂H₆ is a Lewis acid

(D) B₂H₆ can be synthesized from both BF₃ and NaBH₄.

(E) B₂H₆ is planar molecule.

Choose the most appropriate answer from the options given below :

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B₂H₆ has 4 2 c -2e bonds and 2 3c-2e bonds.

Bridging (B-H) bonds have more value of bond- length then terminal (B – H) bonds

Bridging bonds are in one plane, but terminal bonds are in perpendicular plane.

Due to presence of (3c-2e) bonds, it behaves as electrons deficient and prone to get attached by lewis base.

$3 N a B H_{4} + 4 B F_{3} ?_{}^{?} 3 N a B F_{4} + 2 B_{2} H_{6}$

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7 months ago

Which of the following statements are correct?

(A) Both LiCl and MgCl₂ are soluble in ethanol

(B) The oxides Li₂O and MgO combine with excess of oxygen to give superoxide.

(C) LiF is less soluble in water than other alkali metal fluorides.

(D) Li₂O is more soluble in water than other alkali metal oxides.

Choose the most appropriate answer from the options given below :

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Due to higher extent of polarization by Li⁺ and Mg²⁺, LiCl and Mgcl₂ have covalent character. Therefore they are soluble in ethanol.

Due to very high value of lattice energy, LiF is having very less solubility in water.

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The highest industrial consumption of molecular hydrogen is to produce compounds of element :

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The highest industrial consumption of hydrogen gas is in the synthesis of ammonia gas (Having manufacturing of N-based fertizers)

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The highest industrial consumption of molecular hydrogen is to produce compounds of element :

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