Tag: biochemical techniques

Quizzes (6) Questions (139)

Questions Related to biochemical techniques

Multiple choice bio-chemistry biochemical techniques methods of purification of organic compounds methods of purification - organic compounds chromatography

Osazone formation is used to separate and identify.

  1. Alcohols

  2. Carboxylic acids

  3. Carbohydrates

  4. Starch
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Osazones are characteristic crystalline derivatives formed by the reaction of reducing sugars (carbohydrates) with phenylhydrazine. They are used to identify specific sugars.

Multiple choice chemistry organic chemistry : some basic principles and techniques methods of purification of organic compounds methods of purification - organic compounds biochemical techniques

Turpentine oil can be purified by:

  1. steam distillation

  2. vaccum distillation

  3. fractional distillation

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

Steam distillation of a liquid in a current of steam used especially to purify liquids that are not very volatile and are immiscible with water. The boiling point of turpentine oil is between 90 and 115 °C or 195 and 240 °F and is immiscible with water. Thus, it is purified by steam distillation.

Multiple choice bio-chemistry biochemical techniques methods of purification of organic compounds methods of purification - organic compounds chromatography

A mixture of camphor and benzoic acid can be easily separated by?

  1. Sublimation

  2. Fractional distillation

  3. Chemical method

  4. Extraction with solvents
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Aqueous solution of $NaHCO _3$ can be used to separate benzoic acid from its mixture with camphor. Benzoic acid forms water soluble sodium benzoate with $NaHCO _3$. So, A mixture of camphor and benzoic acid can be easily separated by Chemical method.

Option C is correct.

Multiple choice chemistry organic chemistry : some basic principles and techniques methods of purification of organic compounds methods of purification - organic compounds biochemical techniques

Which of the following is not an exact differential?

  1. $dq$
  2. $dG$
  3. $d(\bar { V } )$
  4. $dS$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Exact differential are those function if 
$\cfrac { \delta  }{ \delta T } (\cfrac { \delta f }{ \delta P } )=\cfrac { \delta  }{ \delta P } (\cfrac { \delta f }{ \delta T } )$ where f is the function of P and T. increase of q, it will not be equal , so it will be not exact function.
Multiple choice chemistry organic chemistry : some basic principles and techniques methods of purification of organic compounds methods of purification - organic compounds biochemical techniques

A substance which decomposes at or below its boiling point cannot be purified by?

  1. Steam distillation

  2. Simple distillation

  3. Fractional distillation

  4. Distillation under reduced pressure
Reveal answer Fill a bubble to check yourself
A,B,C Correct answer
Explanation

Steam distillation is used for natural aromatic compounds which are immiscible in water.
Simple and fractional distillation uses the property of difference in the boiling point. These techniques can not be used for the substance which decomposes at or below its boiling point.
Distillation under reduced pressure is basically Vaccum distillation. This method is used to boil such substances without their decomposition

Option A, B and C are the answer.
Multiple choice chemistry organic chemistry : some basic principles and techniques methods of purification of organic compounds methods of purification - organic compounds biochemical techniques

An organic liquid vaporizes at a temperature _________ its boiling point in steam distillation.

  1. above

  2. below

  3. equal to

  4. none of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In steam distillation, the mixture boils when the sum of vapour pressures of water and the organic liquid becomes equal to the atmospheric pressure. Since the vapour pressure of water is appreciably higher than that of the organic liquid, it vaporizes at a temperature much lower than its normal boiling point. 

In this way, many organic compounds insoluble in water can be purified at a temperature well below the point at which decomposition occurs. 

Multiple choice chemistry organic chemistry : some basic principles and techniques methods of purification of organic compounds methods of purification - organic compounds biochemical techniques

In the destructive distillation of coal, at 443-503 K temperature, a middle oil or carbolic oil fraction is obtained. This fraction contains :

  1. Phenol

  2. Xylenes

  3. Naphthalene

  4. Benzene
Reveal answer Fill a bubble to check yourself
A,C Correct answer
Explanation

 (3) Distillation of coal tar : Arenes are isolated by fractional distillation of coal tar,

Table : 

Name of the fraction

Temperature range (K)

Main constituents

Light oil (or crude oil) fraction
Middle oil fraction (Carbolic oil)
Heavy oil fraction (Creosote oil)
Green oil (Anthracene oil)
Pitch (left as residue)

 So at 443-503 K temperature phenol and naphthalene is formed

Hence options A & C are correct.

Multiple choice chemistry organic chemistry : some basic principles and techniques methods of purification of organic compounds methods of purification - organic compounds biochemical techniques

Which of the following procedures will give you water free from all impurities?

  1. Adding chlorine tablets

  2. Distillation

  3. Boiling

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

Distillation procedures will give us water free from all impurities. The distillation process removes almost all impurities from water. Distillers are commonly used for removing nitrate, bacteria, sodium, hardness (dissolved solids), most organic compounds, heavy metals and radionuclides from water. Distillers remove about 99.5% of the impurities from the original water.