B. Magnesium + Hydrogen Sulfide (Reactors) ----> Magnesium Sulfide + Hydrogen (Products)
Im unsure :( maybe try looking up a calorie calculator
Carbon dioxide (CO2)
Argon (Ar)
Hydrogen (H)
Helium (He)
Zn⁰ ----> Zn⁺² + 2e⁻ - oxidation
Hg⁺² + 2e⁻ ----> Hg⁰ - reduction
Zn loses 2 moles of electrons , and Hg gains 2 mole of electrons.
So, number of moles of electrons gained and lost during reaction is equal.
C. Weak acid is the correct answer