Answer:

Explanation:
Molarity refers to a measure of concentration.
Molarity = moles of solute/Litres of solution
Molarity refers to number of moles of solute present in this solution.
In order to find a solution's molarity, use value for the number of moles of solute and the total volume of the solution expressed in liters
As molarity of 2.3 mol of Kl is dissolved in 0.5 L of water,
Molarity = 
The answer is A i think from the options though the answers are worded a bit weird
Answer:
2.765amu is the contribution of the X-19 isotope to the weighted average
Explanation:
The average molar mass is defined as the sum of the molar mass of each isotope times its abundance. For the unknown element X that has 2 isotopes the weighted average is defined as:
X = Mass X-19 * Abundance X-19 + MassX-21 * Abundance X-21
The contribution of the X-19 isotope is its mass (19.00 amu) times its abundance (14.55% = 0.1455). That is:
19.00amu * 0.1455 =
2.765amu is the contribution of the X-19 isotope to the weighted average