Answer:
A
Explanation:
The number of protons indicates the element so we know it's potassium. To get the number of neutrons you subtract the number of protons (19) from the mass number which for potassium is 39.
39-19=20 neutrons
Because you have 18 neutrons then yours would be an isotope.
Answer:
See Explanation
Explanation:
The question is incomplete; as the mixtures are not given.
However, I'll give a general explanation on how to go about it and I'll also give an example.
The percentage of a component in a mixture is calculated as:

Where
E = Amount of element/component
T = Amount of all elements/components
Take for instance:
In 
The amount of all elements is: (i.e formula mass of
)



The amount of calcium is: (i.e formula mass of calcium)



So, the percentage component of calcium is:




The amount of hydrogen is:



So, the percentage component of hydrogen is:




Similarly, for oxygen:
The amount of oxygen is:



So, the percentage component of oxygen is:




Answer:
The average number is given as 48.6
Explanation:
From the question we see that the
Percentage of cis = 47.2%
Percentage of trans = 44.9%
Percentage of vinyl = 7.9%
The chemical reaction equation for the hydrogenation of polybutadiene is shown on the first uploaded image
To obtain the average number of backbone carbon between the ethyl side chains ,we divide the total number of carbon on the backbone by the total number of ethyl group
That is
= (44.9% × 4 + 47.2% ×4 + 7.9% × 2) ÷(7.9% × 1)
= (384.2%/7.7%)
= 48.6
Note : The percentage will cancel out