I believe I know the answer to #4
ANSWER: Two moles to a first approximation
*Disclaimer* I'm pretty sure I'm right, but I could be wrong
Answer:
1 and 4
Explanation:
in both pictures the temperature is cooling down
Answer:

Explanation:
Hello,
In this case, for computing the atom percent, one must obtain the number of atoms of silver, gold and copper as shown below:

Thus, the atom percent turns out:

Best regards.
Answer : (C) "Higher frequencies have larger spaces between lines".
Explanation:
In Young's experiment, the condition for constructive interference is given by :
.........(1)
n is order or number of lines observed
d is distance between slits
is the angle between the path and the line from screen to the slits.
We also know that, 
or

where,
c is the speed of light
is frequency
is wavelength
So, equation (1) turns into


So,

or
Higher frequencies have larger spaces between line.
So, correct option is (C).
Answer: The formula mass (formula weight) of a molecule is the sum of the atomic weights of the atoms in its empirical formula. The molecular mass (molecular weight) of a molecule is its average mass as calculated by adding together the atomic weights of the atoms in the molecular formula.
Hope this helps.... Stay safe and have a great weekend!!!!! :D