7
E) a radical change in the concept of government began to take place
Rubber trees are tapped-that is, cuts are made in the bark so that the latex, a milk -like Juice,
containing about 30 -40% rubber, can be obtained. The latex is then processed by exposing it to
heat and wood smoke,
or by mechanical means, so as to separate the rubber from the 'water,
mineral salts, sugars, resins and protein matters. The rubber obtained in this way is known as,
'crude'-latex is extensively used in industry for making foam rubber, products. footwear, dolls etc.
Untreated crude rubber is naturally soft and lacks the required strength for making into
manufactured articles. To improve
its strength and usefulness, it is vulcanised, or heated with
sulphur, and the proportion of sulphur used determines
the hardness and elasticity of, the rubber.
28 -From its description, we can say that latex ---- .
A) is a hard substance similar to rubber
B)
must be a fairly thin, white liquid
C) is almost entirely pure rubber
D)
is a by -product of rubber
E) is less useful than crude rubber
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