Explanation:
A mixture in which there is uniform distribution of solute particles into the solvent is known as a homogeneous mixture.
For example, sugar dissolved in water is a homogeneous mixture.
On the other hand, a mixture in which there is uneven distribution of solute particles into the solvent is known as a heterogeneous mixture.
For example, sand present in water is a heterogeneous mixture.
Comment on given situations will be as follows.
(a) Air in a closed bottle - It is a homogeneous mixture because there will be even distribution of other gases that are present in air.
(b) Air over New York City - It is a heterogeneous mixture because there will be presence of some dust particles, fog or smoke into the air. Distribution of all these particles will be uneven. This will make air over New York City heterogeneous in nature.
Answer: Molecular mass of the phenol is 94g/mol.
Explanation:
Phenol is an active ingredient in some oral anesthetics used in sore throat sprays.It is used as anesthetics to cure minor sour throat pain , minor mouth irritations etc.
For Example : Cramex , Chloraseptic sprays contains phenol as an active ingredient.
Phenol has a molecular formula of 
Molecular mass of the phenol = 6(mass of carbon)+5(mass of hydrogen)+1(mass of oxygen)+1(mass of hydrogen) = 6(12)+5(1)+1(16)+(1) = 94 g/mol
Answer:
The correct answer is option false.
Explanation:
Molality of the solution defined as moles of substance present in 1 kilogram of solvent.
Moles = 

Mass of percent (w/w%) of the solution is defined as amount of solute present in 100 grams of solution.

So, if want to inter-convert molality into mass percent we can do that without knowing density of solution.
Mass of solution = Mass of solute + Mass of solvent
RMM of CaH2=20+(1x2)=22
Number of moles or formula units
=mass/RMM
=8.294/22
=0.377