What are the well known mathematical tools used to engineer a voltmeter with best performance considering operational and cost restrictions

The amount of heat required to change liquid water to vapor at its boiling temperature is 2256 kj/kg. the amount of heat required to change liquid mercury to its vapor state at its boiling temperature is 295 kj/kg. one kg of each substance is currently at its boiling point. how will the amount of thermal energy required to change each substance from a liquid to a gas differ?

When you see distant streetlights through smog, they look dimmer and redder than they do normally. but when you see the same streetlights through fog or falling snow, they look dimmer but not redder. use your knowledge of the interstellar medium to discuss the relative sizes of the particles in smog, fog, and snowstorms compared to the wavelength of light.

Idon’t know the answer to it and am stuck.