[" 20.What is used as a thermometric liquid in laboratory thermometers "],[qquad " (a) Sodium (b) melted aluminium (c) Shiving water (d) mereury "]

(b) Write the precautions to be followed while using a laboratory thermometer.

A centimetre scale is attached with a thermometer of uniform bore. The thermometer reads 7.3 cm in melting ice, 23.8 cm in boiling water and 3.5 cm in a freezing mixture. What is the temperature of this freezing mixture in ""^(@)C ?

(a) Copper " " (b) Iron (c) Manganin " " (d) Aluminium