Which of the aqueous solutions with the pH values below will liberate hydrogen when it react with magnesium metals?

The aqueous solution with a pH of 3.0 will liberate hydrogen when it reacts with magnesium metal. The liberation of hydrogen occurs because the solution with a pH of 3.0 is acidic. Acids are substances that donate protons (H+) when dissolved in water. When magnesium metal reacts with an acid, such as hydrochloric acid (HCl) or sulfuric acid (H2SO4), hydrogen gas (H2) is produced. In this case, the acidic solution with a pH of 3.0 contains hydrogen ions (H+) that can react with the magnesium metal to produce hydrogen gas (H2) according to the following reaction: Mg(s) + 2H+(aq) → Mg2+(aq) + H2(g) The other solutions with pH values of 6.5, 7.0, and 13.0 are not acidic enough to react with magnesium metal and produce hydrogen gas. A neutral solution with a pH of 7.0 contains an equal concentration of hydrogen ions (H+) and hydroxide ions (OH-), and therefore will not donate enough protons to react with the magnesium metal. A basic solution with a pH of 13.0 contains a high concentration of hydroxide ions (OH-), which will not react with magnesium metal to produce hydrogen gas. It's important to note that the reaction between magnesium metal and an acid can be dangerous and should be conducted with caution under appropriate safety measures.