April 06, 2012

Chemistry in Action Three Marks

1. Give a note on antibiotics.
Many microorganisms (bacteria, fungi and moulds) produce certain chemicals which inhibit the growth or metabolism of some other microorganism. Such chemical compounds are known as antibiotics.
These need be present only in low concentration to be effective in their antibiotic action.
The first antibiotic, discovered by Alexander Fleming in1929, from mould Penicillium notatum, was penicillin.
There are three main sources of antibiotics.
1. Bacteria
2. Fungi and
3. Actinomycetes
Penicillins is the name given to the mixture of natural compounds having the molecular formula C9H11N2O4S - R, and differing only in the nature of R. Depending upon the nature of R, there are at least six natural penicillins.
Uses: Penicillin is extensively used for rheumatic fever, narrowing of heart wall, bronchitis, and pneumonia, etc.
2. Give the preparation of Buna-N rubber.
Buna-N is obtained as a result of copolymerisation of two parts of butadiene with one part of acrylonitrile in the presence of sodium metal.

Uses: for the manufacture of storage tanks for the solvents.
3. How is Buna-S rubber prepared? Give its use. Or Write a brief note on Buna-S.
Buna-S is prepared by the polymerization of butadiene and styrene in presence of sodium metal.

Uses: for the manufacture of tyres, rubber tubes and other mechanical rubber goods.
4. How is nylon-66 prepared? Give its use.
Nylon-66 is prepared by condensing adipic acid with hexamethylenediamine with the elimination of water molecule.
Uses: Nylon-66 is usually fabricated into sheets, bristles for brushes and in textile. Crinkled nylon fibres are used for making elastic hosiery.
5. In what way are antacids important?
After eating oily and spicy food the burning sensation in stomach / food pipe is due to the imbalance in the acidity in the stomach. Antacids contain magnesium and aluminium hydroxides, in addition to flavouring agents and colour which provides relief from such burning sensation.
6. What are anaesthetics? Give example. Or Illustrate with suitable examples the term ‘Anaesthetics’.
The drugs which produce loss of sensation are called anaesthetics.
They are classified into two types.
1. General anaesthetics are the agent, which bring about loss of all modalities of sensation, particularly pain along with ‘reversible’ loss of consciousness.
2. Local anaesthetics prevent the pain sensation in localised areas without affecting the degree of consciousness.
Examples:
1. Nitrous oxide, N2O
2. Chloroform, CHCl3
3. Ether, C2H5–O– C2H5
7. What are antacids? Give an example.
Certain drug formulations provide relief from burning sensation in stomach / food pipe are known as antacids.
Antacids are available in tablet as well as gel / syrup forms. These antacids contain magnesium and aluminium hydroxides, in addition to flavouring agents and colour.
8. What are antioxidants? Give two examples.
1. The substances that act against oxidants are called antioxidants.
2. Antioxidants thus minimise the damage caused by oxidants. Antioxidants protect us against cardiovascular disease, cancer and cataract and they slow down the effect of ageing.
3. Examples:
The most important antioxidants are
1. vitamin C
2. vitamin E and
3. b-carotene.
9. What are artificial sweetening agents? Give two examples.
Certain organic compounds which have been synthesized in laboratories are known to be many times sweeter than cane sugar. Such compounds are called artificial sweetening agents or artificial sweeteners.
Examples:
Some commonly used artificial sweeteners are,
1. Saccharin
2. Dulcin
3. Cyclamate
4. Nectarin and
5. Sucralose
10. What are Chromophores? Give two examples.
An organic compound appears coloured due to the presence of certain unsaturated groups (the groups with multiple bonds) in it. Such groups with multiple bonds are called chromophores.
Examples:

11. Why are iodoform and phenolic solutions called antiseptic?
Iodoform and phenolic solutions render micro organisms innocuous by killing them or preventing their growth.
12. Write a brief note on `Antiseptic'. Or What is antiseptic? Give an example.
Antiseptic is a substance that renders micro organisms innocuous by killing them or preventing their growth. This term is used particularly for preparations applied to living tissues.
Example:
1. Iodoform, CHI3 is used as an antiseptic and its 1% solution is a disinfectant.
2. 0.2 percent solution of phenol acts as an antiseptic and its 1% solution is a disinfectant.
13. Write any three characteristics of dyes.
1. Should have a suitable colour.
2. Should be able to fix itself or be capable of being fixed to the fabric.
3. Should be fast to light.
4. Should be resistant to the action of water, dilute acids and alkalies (all detergents and washing soaps are alkaline in nature).
14. How is Dacron / Terylene / Terene prepared? Give any one of its uses

With Terephthalic acid, Ethylene glycol reacts form the condensation polymer ‘Terylene’ (also known as Dacron or Terene).
 
Extensively used as a Synthetic fiber.
 15. What are antipyretics? Give an example.

Antipyretics are the compounds which are used for the purpose of reducing fever (lowering the body temperature to the normal).
Example
Aspirin, Antipyrine, Phenacetin, Paracetamol
16. What are food preservatives? Give an example.

A chemical substance which prevents the spoilage of food material by destroying the food-spoiling microorganisms in it is called a food preservative.
Example
Sodium benzoate, Potassium metabisulphite, (Salicylic acid, Antioxidants can be used)
17. Define chemotherapy
Treatment of certain diseases by destroying the invading organism without damaging the cells of the host, by the use of certain organic compounds in known as chemotherapy.
OR
The effects of the drugs that are used in the treatment and cure of any specific disease are described by the term chemotherapy.
18. What are Auxochromes? Give an example
The presence of certain groups which are not chromophores themselves, but deepen the colour of the chromogen. Such supporting groups are called auxochromes.
Auxochromes may be acidic (phenolic) or basic.
Example
– OH, – NH2, – NHR, – NR2

3 comments:

  1. exchellant this type questions are very useful to HSC EM STUENDS thanks to publihers

    ReplyDelete
  2. Very useful and would be evenbeter if well organised with keypoints better readability

    ReplyDelete