I think i found your answers
To calculate the average mass of the element, we take the summation of the product of the isotope and the percent abundance. In this case, the equation becomes 186.207=187*0.626+185*x where x is the percent abundance of 185. The answer is 0.374 or 37.4%. This can also be obtained by 100%-62.6%= 37.4%.
Answer:
All alkali and alkaline earth metals dissolves in water to form alkaline solutions.
Explanation:
The alkali metals are found in group one of the periodic table while the alkaline earth metals are found in group 2. These two groups of elements are quite reactive and they react very well with air and water. All the elements in the two groups react with water to give rise to alkaline solutions; solutions whose pH range from 8 to 14.
<u>Answer:</u> The correct answer is Option 4: U
<u>Explanation:</u>
Activation energy is defined as the energy that is given to a chemical system with potential reactants to produce products. It is represented as 
It is represented as the energy from the reactants to the activated complex.
Reverse reaction is defined as the reaction in which the products formed become reactants and leads to the formation of reactants back.
So, here, the activation energy of the reverse reaction is the energy between the products and the activated complex, which is represented as letter U in the given graph.
Hence, the correct answer is Option 4: U