Replicate water samples are analyzed for water hardness with the following results: 102.2, 102.8, 103.1 and 102.5ppm CaCO3. Calculate:-
(a) The standard deviation
(b) The relative standard deviation
(c) The standard deviation of the mean
(d) The relative standard deviation of the mean.

Ans. : frostbite is when exposure to cold temperatures causes freezing to the skin or other tissues. it most commonly affects the hands, feet, and face. the longer areas are exposed to cold, typically the worse the frostbite. the water temperature used for rewarming a frostbitten part should be : (102 -105) f degrees.

In reversible reaction chemistry equilibrium is attained when the forward and reverse reactions are taking place at the same rate, thus, the concentrations of reactants and products remain the same. a reversible reaction is a chemical reaction where the reactants form products that, in turn, react together to give the reactants back. in irreversible reactions on the other hand, the reactants react to form the products, which cannot revert back into reactants.