<u>Answer:</u> The average rate of the reaction is 
<u>Explanation:</u>
To calculate the molarity of hydrogen gas generated, we use the equation:

Moles of hydrogen gas = 
Volume of solution = 250 mL = 0.250 L (Conversion factor: 1 L = 1000 mL)
Putting values in above equation, we get:

Average rate of the reaction is defined as the ratio of concentration of hydrogen generated to the time taken.
To calculate the average rate of the reaction, we use the equation:

We are given:
Concentration of hydrogen generated = 0.1564 M
Time taken = 20.0 minutes
Putting values in above equation, we get:

Hence, the average rate of the reaction is 
Answer:
The answer is
D. Main sequence
Explanation:
Main sequence stars can be between one thousand times dimmer and one million times brighter than the Sun.
What is main sequence stars?
A main sequence star is any star that is fusing hydrogen in its core and has a stable balance of outward pressure from core nuclear fusion and gravitational forces pushing inward.
Answer:
The uranium in the sample of the compound is radioactive
Explanation:
Some atoms can split on their own. Some split when bombarded by energetic particles. Such atoms are said to be radioactive.
Radioactivity is borne out of the drive of an atom to reach stabillity. Every atom have a specific neutron/proton ratio which ensures stability of the nucleus. A nucleus with a stability ratio different from that which makes it stable will become unstable and split into one or more other nuclei with emissons of energetic particles.
Note: neutrons and protons dictates the mass of an atom. They are located in the nucleus which is the site for nuclear radioactive reactions.
C) by adding lava.
Heat, gasses and water vapour do not create land. Lava can solidify, become a rock,which can become new lan