Question

If $10\mathrm{ml}$ of ${\mathrm{H}}_2{\mathrm{SO}}_4$ is mixed with $10\mathrm{ml}$ $\mathrm{Mg}{\left(\mathrm{OH}\right)}_2$ the same concentration the resultant solution will give the following color of universal indicator

• A. Red
• B. Yellow
• C. Green
• D. Blue

Answer 1

The correct option is C

Green

The explanation for the correct option:

Option (C): Green

• A universal indicator is a set of indicators that show a color change in a solution and can be used to detect whether it is acidic or basic.
• On dissociation, sulfuric acid produces $\underset{\mathrm{Sulfuric}\mathrm{acid}}{{\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{l}\right)}\to \underset{\mathrm{Hydrogen}\mathrm{ion}}{2{\mathrm{H}}^{+}}+\underset{\mathrm{Sulfate}\mathrm{ion}}{{{\mathrm{SO}}_4}^{2-}}$
• Dissociation of magnesium hydroxide$\underset{\mathrm{Magnesium}\mathrm{hydroxide}}{\mathrm{Mg}{\left(\mathrm{OH}\right)}_2\left(\mathrm{l}\right)}\to \underset{\mathrm{Magnesium}\mathrm{ion}}{{\mathrm{Mg}}^{+2}}+\underset{\mathrm{Hydroxide}}{2{\mathrm{OH}}^{-}}$
• Adding both the equations we get a neutralization reaction resulting in salt and water as its products

$\underset{\mathrm{Hydrogen}\mathrm{ion}}{2{\mathrm{H}}^{+}}+\underset{\mathrm{Sulfate}\mathrm{ion}}{{{\mathrm{SO}}_4}^{2-}}+\underset{\mathrm{Magnessium}\mathrm{ion}}{{\mathrm{Mg}}^{+2}}+\underset{\mathrm{Hydroxide}\mathrm{ion}}{2{\mathrm{OH}}^{-}}\to \underset{\mathrm{Magnesium}\mathrm{sulfate}}{{\mathrm{MgSO}}_4\left(\mathrm{s}\right)}+\underset{\mathrm{water}}{2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}$

• In a neutral solution or at pH$=7$, the universal indicator turns green.
• Hence it is the correct option.

The explanation for incorrect options:

Option (A): Red

• The Universal indicator becomes red in a highly acidic medium.
• Hence it is an incorrect option.

Option (B): Yellow

• The universal indicator becomes yellow for a less acidic solution
• Hence, it is an incorrect option

Option (D): Blue

• The universal indicator turns blue for basic solutions.
• Hence, it is an incorrect option.

Therefore, for the resulting solution, the universal indicator will turn green.