the answer to the first one is D and the second one is the first one
Given :
Number of moles , n = 36.25 mol .
Molarity , M = 1.25 M .
To Find :
The volume of water required .
Solution :
Moarity is given by :
So , 
Here , n is number of moles and M is molarity .
Putting all values in above equation , we get :
Therefore , volume of water required is 29 L .
Atomic mass of boron = 10.81
<h3>What are Isotopes?</h3>
Isotopes are variants of a particular element in which they have the same number of protons but differ in the number of neutrons in the atom.
So, here as we said we have isotopes which weigh 10.01 and 11.01.
Given,
relative abundance of B-10 = 10.1 amu
relative abundance of B- 11 = 11.01 amu
percentage of B-10 = 20%
percentage of B-11 = 80%
Then the relative atomic mass depends upon the relative abundance of various isotopes of that particular element. Suppose an element consists of two isotopes and average atomic mass is equal to
(Relativeabundance(1)×Atomicmass(1)+Relativeabundance(2)×Atomicmass(2)) / (Relativeabundance(1)+Relativeabundance(2))
Atomic mass of boron = (20 × 10.01 + 80 × 11.01) / (80 + 20 )
= 1081/100
= 10.81
To learn more about atomic mass from the given link
brainly.com/question/3187640
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Answer:
Covalent molecular structures are compounds containing molecules with covalent bonds. Covalent network structures are compounds composed of a network structure with covalent bonds between atoms throughout the material.
Explanation:
