Look at the reaction below. Upper H subscript 2 upper S upper O subscript 4 (a q) plus upper Upper M g (s) right arrow Uper M g upper S upper O subscript 4 (a q) plus upper H subscript 2 (g). Which substance is the acid in the reaction? Mg(s) H2(g) MgSO4(aq) H2SO4(aq)

H2SO4(aq)

Explanation:

The balanced equation for the reaction is given below:

H2SO4(aq) + Mg(s) —> MgSO4(aq) + H2 (g)

An acid is a substance which dissolves in water to produce hydrogen ion, H+ as the only positive ion.

To know which of the substance is acid, let us dissolve them in water to see which will produce hydrogen ion, H+ as the only positive ion.

This is illustrated below:

H2SO4(aq) —> 2H+(aq) + SO4^2-(aq)

Mg(s) + 2H2O(l) —> Mg(OH)2(aq) + H2(g)

MgSO4(aq) —> Mg^2+(aq) + SO4^2-(aq)

H2 is insoluble in water.

From the above, only H2SO4 produces hydrogen ion H+ on dissolution in water. Therefore, H2SO4 is an acid

the correct answer is:

a. formation of precipitation