It is actually Group 3A elements. I just took the test.
Answer: M-18
Explanation:
The mass spectra of alcohols often fail to exhibit detectable M peaks but instead show relatively large __M-18___ peaks.
Mass spectroscopy is used to determine the molecular mass and molecular formula of a sample.
When the mass spectra of alcohols do not show detectable M peaks, they show relatively large M-18 peaks.
Answer:
a) Step 1:

Step 2:

b) The overall balanced reaction for given process is ;

Explanation:
a)
Galena = 
Lead(II) oxide = 
Sulfur dioxide = 
Step 1:
Roasting the galena in oxygen gas to form lead(II) oxide and sulfur dioxide.
Balanced equation of step 1:
..[1]
Step 2:
Heating the metal oxide with more galena forms the molten metal and more sulfur dioxide.
Balanced equation of step 2:
..[2]
b)
For over all reaction add [1] and [2]. The overall balanced reaction for given process is ;

1 is chemical energy cause thats what gas and electric stoves are
2 is convection
3 is c