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Multiple choice chemistry world energy needs coal petroleum non-renewable sources of energy

The process of crystallization is used to obtain pure solids because:

  1. iIt is better than evaporation

  2. impurities are filtered completely

  3. ultra pure crystals are formed

  4. decomposition does not take place
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Since crystallization generally produces salts which are crystalline in state or $100$ percent purity in state.

Multiple choice chemistry world energy needs coal petroleum non-renewable sources of energy

What is the method to separate two compounds with different solubilities in a solvent? 

  1. Sublimation

  2. Crystallization

  3. Chromatography

  4. Distillation
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Two compounds which have different solubilities in a solvent S can be separated from each other by Fractional Crystallisation. The process involves a series of repeated-crystallisations. The mixture of the two compounds in the solvent S is heated so as to make it saturated. When the hot solution is allowed to cool, the less soluble substance crsytallises out first while the more soluble substance remains in the solution. The crystals of first compound are separated from the mother liquor and the mother liquor is again concentrated and allowed to cool when the crystals of the 2nd compound are obtained.

Multiple choice chemistry world energy needs coal petroleum non-renewable sources of energy

Separation of a mixture into its components, whose boiling points are different, is called :

  1. fractional distillation

  2. destructive distillation

  3. displacement

  4. filtration
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Separation of a mixture into its components whose boiling points are different is called Fractional distillation.
This method is used for separating a mixture of two or more volatile liquids both having close boiling points. The boiling points of two components differ by 10-15 K. For example, acetone and methanol with boiling points 329 K and 338 K can be separated  by this method. This method is used for distillation of petroleum, coal tar and crude alcohol.

Multiple choice chemistry world energy needs coal petroleum non-renewable sources of energy

90% benzol is named so because 100. c.c of the fraction when distilled below 100 deg C gives 90 c.c of toluene.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

90% benzol is named so because 100. c.c of the fraction when distilled below 100 deg C gives 90 c.c of distillate.
90% benzol contains 70% benzene, 24% toluene and 3-5% xylene.


Multiple choice chemistry world energy needs coal petroleum non-renewable sources of energy

Which of the following represents the chief constituents of green oil?

  1. benzene, toluene, xylenes, etc.

  2. phenol, naphthalene, etc.

  3. cresols, naphthalene, etc.

  4. anthracene, phenanthrene, etc.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Anthracene, phenanthrene, etc. represent the chief constituents of green oil.

Multiple choice chemistry world energy needs coal petroleum non-renewable sources of energy

Which of the following represents the chief constituents of creosote oil?

  1. Benzene, toluene, xylenes, etc.

  2. Phenol, naphthalene, etc.

  3. Cresols, naphthalene, etc.

  4. Anthracene, phenanthrene, etc.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Cresols, naphthalene, etc. represents the chief constituents of Creosote oil.

Multiple choice chemistry world energy needs coal petroleum non-renewable sources of energy

Ammonia liquor is prepared by dissolving:

  1. ammonia gas in alcohol

  2. ammonia gas in water

  3. ammonia gas in hydrochloric acid

  4. ammonia gas in caustic soda solution
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Ammonia liquor is prepared by dissolving Ammonia in water. Ammonia liquor is also known as ammonia water or some times known as ammonium hydroxide.
In aqueous solution, ammonia deprotonates a small fraction of the water to give ammonium and hydroxide according to the following equilibrium:
$ NH _3 +H _2O\rightarrow NH _4^{+} + OH^{-}$

Multiple choice chemistry world energy needs coal petroleum non-renewable sources of energy

During fractional distillation, at what temperature range is carbolic oil or middle oil collected?

  1. upto 170$^o$
  2. 170 - 230 $^o$
  3. 230 - 270 $^o$
  4. 270-360$^o$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

During fractional distillation,  carbolic oil or middle oil is collected up to 170 - 230 $^o$.

Above this temperature, the Anthracene oil is obtained.