Tag: chemistry

Questions Related to chemistry

A public health inspector suspects that in addition to two harmless dyes (boiling points $69\ ^oC$ and $71\ ^oC$), a lollipop also contains a poisonous green dye (boiling point $73\ ^oC$). Which of the following can be used to confirm his suspicion?

chemistry basic analytical techniques filtration and crystallisation other methods of separation separation techniques

  1. Fractional distillation

  2. Paper chromatography

  3. Filtration

  4. Crystallization

Show answer
Correct Option: B
Explanation:

A public health inspector suspects that in addition to two harmless dyes(boiling points 69 C and 71 C), a lollipop also contains a poisonous green dye (boiling point 73 C). Paper chromatography can be used to confirm his suspicion. Here, different dyes will have different affinity for paper (stationary phase) and solvent (mobile phase). Fractional distillation is used when individual components of mixtures have boiling points more than 30 C. Filtration and crystallisation are used in separation / purification of solid from liquid.

John tried to separate sugar from its solution using the evaporation method. However, he was unsuccessful. Which of the following is the likely reason?

chemistry basic analytical techniques filtration and crystallisation other methods of separation separation techniques

  1. There was insufficient sugar in the solution

  2. He had forgotten to stir the solution during heating

  3. The sugar had decomposed

  4. The sugar had vaporised.

Show answer
Correct Option: C
Explanation:
John tried to separate sugar from its solution using the evaporation method. However, he was unsuccessful as the sugar had decomposed. When you sugar (sucrose) is heated, it undergoes dehydration. The crystalline structure breaks down. Molecules decompose into glucose and fructose and then lose water and polymerize to form caramel, which is a red-orange colored solid.

Sand that is needed for a project has some common salt accidentally mixed with it. which of the following processes need to be used to separate sand and salt?
1. Filtration
2. Evaporation
3. Distillation
4. Crystallisation

chemistry basic analytical techniques filtration and crystallisation other methods of separation separation techniques

  1. 1, 2

  2. 1,2 and 4

  3. 1, 2 and 3

  4. 1,2,3 and 4

Show answer
Correct Option: A
Explanation:

To separate the mixture of salt and sand;

first we will make the aqueous solution, salt gets dissolved in water and sand particle remain undissolved,
so, the misture can be separated by filtration and evaporation.

Modern oil-based paints contain oils that can dry to form strong, adhesive films by cross-linking of fatty acid chains. Some of these drying oils' are mentioned here. Can you pick the false one?

chemistry petrochemicals and polymers food spoilage and food preservation methods of preserving food chemicals in food

  1. Linseed oil

  2. Turpentine oil

  3. Soyabean

  4. Castor oil

Show answer
Correct Option: B
Explanation:

Drying oils are prone to hardening upon exposure to air, due to free radical base polymerization, thus forming a flexible, transparent and waterproof film. This property is exhibited by linseed, turpentine and soybean oils. 

Stearic acid is.

chemistry petrochemicals and polymers food spoilage and food preservation methods of preserving food chemicals in food

  1. An unsaturated fatty acid

  2. A saturated fatty acid

  3. Essential fatty acid

  4. A simple lipid

Show answer
Correct Option: B

________ act as protective agent on the surface of animals and plants.

chemistry petrochemicals and polymers food spoilage and food preservation methods of preserving food chemicals in food

  1. Carbohydrates

  2. Vitamins

  3. Nucleic Acids

  4. Wax

Show answer
Correct Option: D
Explanation:

Wax act as a protective agent on the surface of animals and plants. It protects animals and plants from excessive loss of moisture. It protects the plants and fruits from becoming infected with fungi and bacteria.


Wax contains esters of long chain fatty acids and long chain alcohols or sterol.

Hence, option D is correct.

High molecular weight alcohols are present in:

chemistry petrochemicals and polymers food spoilage and food preservation methods of preserving food chemicals in food

  1. waxes

  2. fats

  3. oils

  4. phospholipids

Show answer
Correct Option: A
Explanation:

waxes are monoglycerides, these are form by the condensation reaction between monohydroxy alcohol and fatty acid, this is the high molecular weight compound.

Example- Bee wax 
( Hexacosyl palimitate $\rightarrow$ Hexacosyl alcohol+ Palmitic acid)
$C _{26}H _{53}OH + C _{15}H _{31}COOH \overset{-H _2O}\rightarrow C _{26}H _{53}COOC _{15}H _{31}$ 

Four oils $A, B, C$ and $D$ have the following values of melting points.
(a) $258$ K (b) $273$ K (c) $295$ K (d) $303$ K
Among these, which oil is prohibited from consumption by cardiac patients?

chemistry petrochemicals and polymers food spoilage and food preservation methods of preserving food chemicals in food

  1. a

  2. b

  3. c

  4. d

Show answer
Correct Option: D
Explanation:

The oils having higher unsaturation in the fatty acid component have very low melting points. Hence, on the consumption of these oils there is less chance of blockage of blood vessels. The saturated oils have higher melting points and they get solidified easily. Therefore they block the blood vessels and so are prohibited from consumption by cardiac patients. Hence oil D is prohibited from consumption by cardiac patients.

A concentrated solution contains high amount of ________.

chemistry element, compound and mixture different types of solutions various mixtures introduction to solutions

  1. solvent

  2. solute

  3. both solute and solvent

  4. none of these

Show answer
Correct Option: B
Explanation:

A concentrated solution contains the maximum amount of solute that can be dissolved because solubility depends on temperature, a solution that is concentrated at one temperature may not be concentrated at a higher temperature.

Which of the following is used as antifreeze on cars for cooling the engine?

chemistry element, compound and mixture different types of solutions various mixtures introduction to solutions

  1. $10\%$ (V/V) ethanol solution in water

  2. $35\%$ (V/V) ethanol solution in glycol

  3. $45\%$ (V/V) ethanol solution in glycol

  4. $20\%$ (V/V) ethanol solution in water

Show answer
Correct Option: A