4.648 gm of solute is needed to make 37.5 mL of 0.750 M KI solution.
Solution:
We will start with the Molarity

Also we know 1000 ml = 1 L
Therefore 37.5 ml by 1000ml we obtained 0.0375L
Equation for solving mole of solute

Now, multiply 0.750M by 0.0375
Substitute the known values in the above equation we get

Also we know that Molar mass of KI is 166 g/mol
So divide the molar mass value to get the no of grams.

So 4.648 gm of Solute is required for make 37.5 mL of 0.750 M KI solution.
Answer: It will take 29 years for a 10.0-gram sample of strontium-90 to decay to 5.00 grams
Explanation:
Radioactive decay process is a type of process in which a less stable nuclei decomposes to a stable nuclei by releasing some radiations or particles like alpha, beta particles or gamma-radiations. The radioactive decay follows first order kinetics.
Half life is the amount of time taken by a radioactive material to decay to half of its original value.
Half life is represented by 

= rate constant
Given : Strontium-90 decreases in mass by one-half every 29 years , that is half life of Strontium-90 is 29 years.
As half life is independent of initial concentration, it will take 29 years for a 10.0-gram sample of strontium-90 to decay to 5.00 grams as the amount gets half.
I have a feeling that #2 is the one.
Answer:
HF has the higher boiling point because HF molecules are more polar. Part B: CHBr3 molecules possess stronger intermolecular interaction due to higher molar mass than CHCl3
Explanation:
Fluorine is more electronegative than chlorine. This implies that HF is more polar and possess stronger hydrogen bonds than HCl molecules.
In part B, the magnitude of dispersion forces depend on molar mass, the greater the molar mass, the greater the magnitude of dispersion forces between molecules, hence CHBr3 has a greater boiling point than CHCl3