Question

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EXERCISE 14.
Shart Aawwer Type Questions
1. A metal ball is heated and its temperature is noted at different intervals as shown in the
following table :
Time ) in seconds
Temperature in C
16
2
19
4
23
6
27
10
35
15
Draw the corresponding temperature-time graph and answer the following questions:
(1) What is the temperature of the ball when t = 5 sec ?
(ii) What is temperature of the ball when t = 12 see?
(in After how many seconds the temperature of the ball is 40°C
(iv) What is t when T = 55°C ?
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Answer 1

Plaster of Paris is calcium sulphate hemihydrate (CaSO4. V2H2O) while gypsum is calcium sulphate dihydrate (CaSO4.2H2O). Gypsum, when heated at a temperature of about 380K, changes to Plaster of Paris. Plaster of Paris, when mixed with water, changes into hard mass called gypsum. Plaster of Paris is used in hospitals for setting fractured bones.It is used for making moulds or casts for toys pottery, ceramics etc.