Answer: 10.2 grams
Explanation:
The balanced chemical reaction is :

According to the ideal gas equation:

P = Pressure of the gas = 740 torr = 0.97 atm (760torr=1atm)
V= Volume of the gas = 12.0 L
T= Temperature of the gas = 19°C = 292 K 
R= Gas constant = 0.0821 atmL/K mol
n= moles of gas


According to stoichiometry:
2 moles of hydrogen are generated by = 1 mole of 
Thus 0.48 moles of hydrogen are generated by =
moles of 
Mass of 
Thus 10.2 grams of
are needed to generate 12.0 L of hydrogen gas if the pressure of hydrogen is 740. torr at 19°C
Answer:
The correct matching of the air mass and the letters in the word bank are given as follows;
1. Warm and humid ↔ D
2. Extremely cold and dry ↔ B
3. Cold and dry ↔ A
4. Cold and humid ↔ C
5. Warm and dry ↔ E
Where;
A Represents continental polar
B Represents Artic
C Represents Maritime Polar
D Represents Maritime Tropical
E Represents Continental Tropical
Explanation:
A. A continental polar is one that can be described as a cold and dry climate as the region is located at a further away from the oceanic water bodies that add humidity to the climate
B. The regions of the Artic and the Antarctic have very limited amount of precipitation every year because the air is very cold as well as dry
C. A polar climate is a cold climate region, while a maritime climate is humid.
Therefore, the maritime polar climate combines both cold and humid conditions
D. A warm and humid region has high rainfall and humidity, as such the maritime climate which are humid and the tropical climate, which are warm, combine to give a warm and humid climate
E. The continental tropical climate can be described as warm and dry, compared to the continental water bodies, due to the location being distant from and therefore, the absence of high moisture containing wind that comes from the oceans.
Density is the ratio of mass to the volume.
The mathematical expression is given as:

Now, density of isooctane = 
Volume = 
Since, 1 gallon = 3.78 L
So, 3.8 gal = 
= 
As, 1 L = 1000 mL
Therefore,
= 
Volume in mL = 
Put the values,


= 
Hence, mass of 3.8 gal of the gasoline is
.
Answer:
Balanced reaction:
3 H2 (g) + N2 (g) → 2 NH3 (g)
Use stoichiometry to convert g of H2 to g of NH3. The process would be:
g H2 → mol H2 → mol NH3 → g NH3
12.0 g H2 x (1 mol H2 / 2.02 g H2) x (2 mol NH3 / 3 mol H2) x (17.03 g NH3 / 1 mol NH3) = 67.4 g NH3
Explanation: See above
Hope this helps, friend.