The mole fraction of oxygen in dry air near sea level is 0.20948. the concentration of
oxygen is molecules per liter, assuming an atmospheric pressure of 739 torr and
a temperature of 29.5°c
a) 6.23
b) 0.00819
c) 4.93 × 1021
d) 3.75 × 1024
e) 5.07 × 1022

C,d,or e you can use the process of elimination to decide...

N sub air = ( P ) ( V ) / ( R ) ( T ) 

n sub air = ( 739 / 760 ) ( 1.000 ) / ( 0.08205 ) ( 28.5 + 273.2 ) 

n sub air = 0.03928 mol per L 

R = universal gas constant = 0.08205 atm - L per mol - deg K 

Find moles O2 per liter : 
... 

n sub O2 = ( y sub O2 ) ( n sub air ) 

n sub O2 = ( 0.20948 ) ( 0.03928 ) 

n sub O2 = 0.008228 moles O2 per L 

Now apply Avogadro's Number to get the O2 molecules per liter : 
... 

N sub O2 = ( n sub O2 ) ( N sub AVO ) 

N sub O2 = ( 0.008228 ) ( 6.022 x 10^23 ) 

N sub O2 = 4.96 x 10^21 O2 molecules per liter

It's C.

You will hear a hissing sound because of the carbon dioxide escaping the can or bottle

Well the magnitude of its acceleration related to that car starts with the oil change like when you have to change the oil in your car you have to make sure that your precious car is starting really propley and very well