To Find :
The volume of 12.1 moles hydrogen at STP.
Solution :
We know at STP, 1 mole of gas any gas occupy a volume of 22.4 L.
Let, volume of 12.1 moles of hydrogen is x.
So, x = 22.4 × 12.1 L
x = 271.04 L
Therefore, the volume of hydrogen gas at STP is 271.04 L.
The answer is C, hydrogen gas. This is because in single replacement reactions, the single element (here Magnesium) replaces whichever element in the compound it corresponds to. Because Mg loses electrons since it’s a metal, it will replace the element which also loses electrons, which is Hydrogen here. So when they switch places, MgCl2 and H2 are made— and H2 is the hydrogen gas.
<h2>Answer:</h2>
<em><u>The kinetic energy of the air molecules in the cave is less than the kinetic energy of molecules outside the cave.</u></em>
<h3>Explanation:</h3>
The kinetic energy of any molecule is directly proportional to the temperature of the gas.
Temperature of a gas is the heat energy provided to the molecules. As the temperature energy increase the molecules of the gas will move fastly and collide with each other.
So we can know the kinetic energy of molecules in the gas by measuring its temperature.
Hence the temperature of the cave is less than outside, so the kinetic energy will also be low.
There are many ways which can <span>lead us to believe a chemical reaction has occurred. I am discussing few of them.
Change in Color:
Few reactions proceed with the change in colour. When Bromine Water (yellow-Brown) is treated with unsaturated compounds, the color disappear as the reaction is completed.
Gas Production:
Some reactions proceed with the elimination of gas i.e. CO</span>₂ , H₂, N₂, H₂O e.t.c.
Temperature Change:
Some reactions evolve or absorb heat when proceed. This change is the evidence of progress of reaction.
Thin Layer Chromatography:
Very important technique in detecting the progress of reaction by determining the number of spots for UV active compounds on TLC plate. Even non UV active compounds can be detected by using other locating agents.
Instrumental Techniques:
Modern techniques like IR, MS, NMR, UV spectroscopy can be used to detect the progress of reaction.
Answer:
A. Kinetic energies of molecules increase.
B. Speeds of molecules increase.
C. Number of collisions per second increase.
