Explanation
 (a) A clinical thermometer has small temperature range. The glass will crack/burst due to excessive pressure created by expansion of mercury.
(b) Increase in pressure
 (i) increases the boiling point; 
 (ii) decreases the melting point. 

(c) At the boiling point of pure water, the saturated vapour pressure (s.v.p) of the water is equal to the external atmospheric pressure.  
(d) Diagram

Volume V is proportional to length Ɩ stated or implied 
(i)  P\(_1\)V\(_1\) = P\(_2\)V\(_2\) implies P\(_1\)P\(_1\) = P\(_2\)P\(_2\) 
(76 + 20) 15 = 76 x L\(_2\) 
 Ɩ\(_2\) = 96 x 15
    76
 Ɩ\(_2\) = 18.95 cm
(ii) P\(_1\)L\(_1\) = P\(_3\) L\(_3\) 
= (76 + 20) 15 = (76 – 20) x Ɩ\(_3\)
 Ɩ\(_3\) = 96 x 15 
              56
Ɩ\(_3\) = 25.7l cm

