I got on here because I don't understand the question but I did my best to answer because I noticed you asked 3 days ago. IF I'm right the answer is D. My diagram shows
A at -50 °C
B at 0 °C
C at 50 °C
D at 100 °C (gas to liquid or liquid to gas)
And E at 150 °C
So I hope I'm right because I'm answering the same question.
Answer: They are arranged by atomic number.
_Mg + _HCL = _MgCl2 + H2
Separate the terms on each side:
_Mg + _HCl = _MgCl2 + H2
Mg- 1 Mg-1
H-1 H-2
Cl-1 Cl-2
Mg is balanced on both sides so move on to the next (put a 1 in the space).
1Mg
There are two H's and two Cl's on the results side, so to balance the equation put a 2 as a coefficient for HCl and it'll all balance out.
2HCl
Balamced equation will be:
1Mg + 2HCL = 1MgCl2 + H2
