Answer:
82.25 moles of He
Explanation:
From the question given above, the following data were obtained:
Volume (V) = 10 L
Mass of He = 0.329 Kg 
Temperature (T) = 28.0 °C
Molar mass of He = 4 g/mol
Mole of He =? 
Next, we shall convert 0.329 Kg of He to g. This can be obtained as follow:
1 Kg = 1000 g
Therefore, 
0.329 Kg = 0.329 Kg × 1000 g / 1 Kg
0.329 Kg = 329 g
Thus, 0.329 Kg is equivalent to 329 g. 
Finally, we shall determine the number of mole of He in the tank. This can be obtained as illustrated below:
Mass of He = 329 g 
Molar mass of He = 4 g/mol
Mole of He =?
Mole = mass / molar mass 
Mole of He = 329 / 4
Mole of He = 82.25 moles 
Therefore, there are 82.25 moles of He in the tank. 
 
        
             
        
        
        
The answer would be B. :)
        
             
        
        
        
Answer:
For H2O, there is one atom of oxygen and two atoms of hydrogen. A molecule can be made of only one type of atom. In its stable molecular form, oxygen exists as two atoms and is written O2. to distinguish it from an atom of oxygen O, or ozone, a molecule of three oxygen atoms, O3.
Explanation:
 
        
             
        
        
        
¡Hellow!
For this problem, first, lets convert the seconds in hours:
5,4x10³ 5400
 5400
h = sec / 3600
h = 5400 s / 3600
h = 1,5 
Let's recabe information:
d (Distance) = 386 km
t (Time) = 1,5 h
v (Velocity) = ?
For calculate velocity, let's applicate formula:
                                                     
Reeplace according we information:
386 km = v * 1,5 h
v = 386 km / 1,5 h
v = 257,33 km/h
The velocity of the train is of <u>257,33 kilometers for hour.</u>
<u></u>
Extra:
For convert km/h to m/s, we divide the velocity of km/h for 3,6:
m/s = km/h / 3,6
Let's reeplace:
m/s = 257,33 km/h / 3,6
m/s = 71,48
¿Good Luck?