Time taken = 3 hours
<h3>Further explanation</h3>
Given
speed : 75 mph
distance : 225 miles
Required
time taken
Solution
An equation of constant velocity motion

d = distance = m
v = speed = m / s
t = time = seconds
Input the value :
t = d : v
t = 225 miles : 75 miles/hour
t = 3 hours
Assume 1 liter = 1 kilogram of water = 1000 grams of water.
Part A)
MW of hydrogen is 1.008g/mol, and oxygen is 16.00g/mol.
Find the MW of water by
2*(1.008) + (16.00) = 18.016g/mol.
Convert 1000g H2O to moles :
(1000g H2O)*(1mol H2O / 18.016g H2O) = 55.51 mol
Part B)
Using the answer from part A and Avogadro's number:
(55.51mol)*(6.022*10^23) =
3.343*10^25 molecules.
Hope this is helpful
Thermodynamics, Nuclear Physics, Quantum Physics, Astronomy and Astrophysics
As it is located at 7s ^2 it will have 2 valence electrons that due to its position in the s orbital it will be prone to losing them to obtain a noble gas configuration.