The anser is- Carbon dioxide
Answer: Freezing point of a solution will be 
Explanation:
Depression in freezing point is given by:

= Depression in freezing point
i= vant hoff factor = 1 (for non electrolyte)
= freezing point constant = 
m= molality

Weight of solvent (benzene)= 1480 g =1.48 kg
Molar mass of solute (octane) = 114.0 g/mol
Mass of solute (octane) = 220 g



Thus the freezing point of a solution will be 
We know that density = mass /volume
so
mass=volume*density
volume=mass/density
so c is wrong
Answer: a. 79.6 s
b. 44.3 s
c. 191 s
Explanation:
Expression for rate law for first order kinetics is given by:
where,
k = rate constant
t = age of sample
a = let initial amount of the reactant
a - x = amount left after decay process
a) for completion of half life:
Half life is the amount of time taken by a radioactive material to decay to half of its original value.
b) for completion of 32% of reaction
c) for completion of 81 % of reaction
D. Is a fly shot effective in preventing the flu?
Answer A touches on the topics of economics and industrial feasibility of the flu shot.
B is more of an ethical / situational question.
C is a social question.
D is the only question which focuses on the science of microbiology and medicine.