Narcotic drugs: [Opioids]
(i) These are narcotic analgesics. These relieve pain and produce sleep. These drugs are addictive. In poisonous dose, these produces coma and ultimately death.
(ii) They are used for either short-term or long term relief of severe pains. They are mainly used for post operative pain, pain of terminal cancer.
(iii) Eg: Morphine, Codeine
Non-narcotic drugs:
(i) These are non- narcotic analgesics. These reduce the pain without causing impairment of consciousness.
(ii) They alleviate pain by reducing local inflammatory responses.
(iii) These are used for short-term pain relief and for modest pain like headache, muscle strain, bruising or arthritis.
(iv) These drugs have many other effects such as reducing fever (antipyretic) and preventing platelet coagulation (eg. aspirin).
(v) These reduce fever by causing the hypothalamus to over ride a prostaglandin - induced increase in temperature.
(vi) Eg. Aspirin, Paracetamol, Ibuprofen. There are two types in it.
a) Anti inflammatory: eg: Aspirin, Paracetamol
b) Non steroidal anti -inflammatory drugs: (NSAIDs) eg: Ibuprofen

a) Bakelite - Cross linked polymer
b) Nylon - Linear polymer
c) polythene (HDPE) - Linear polymer
d) polythene (LDPE) - Branched polyner

(i) Monomers :Ethylene glycol and terepathalic acid (or) dimethyl terephthalate.
(ii) Catalyst : Zinc acetate and antimony trioxide.
(iii) Temperature : 500 K
(iv) Product : Terylene

(v) Uses : blending with cotton or wool fibres and as glass reinforcing materials in safety helmets

(i) A polymer containing two or more different kinds of monomer units is called a copolymer.
(ii) For example, SBR rubber(Buna-S) contains styrene and butadiene monomer units.
(iii) Copolymers have properties quite different from the homopolymers.
(iv) Mixture of styrene and 1,3 butadiene to form a copolymer (Buna -S)
Preparation of Buna-S:
It is a co-polymer. It is obtained by the polymerisation of buta -1,3 - diene and styrene in the ratio 3: 1 in the presence of sodium.