When zeolite, which is hydrated sodium aluminium silicate, is treated with hard water, the sodium ions are exchanged with

• A

  ${\mathrm{H}}^{+}$ions
• B

  $\mathrm{C}{\mathrm{a}}^{2+}$ions
• C

  $\mathrm{M}{\mathrm{g}}^{2+}$ions
• Correct answer
  D

  Both $\mathrm{C}{\mathrm{a}}^{2+}$ and $\mathrm{M}{\mathrm{g}}^{2+}$

Hence, the correct answer is option: 'D'.