Question

one calcium atom (ca⁺²) will combine with which of the following atoms in a one - to - one ratio? select one: a. be⁺² b. o⁻² c. cl⁻ d. na⁺

Explanation:

Step1: Recall charge neutrality rule

Ionic compounds require total positive charge = total negative charge.

Step2: Analyze each option

• a. $\text{Be}^{+2}$: Both positive, no neutral compound.
• b. $\text{O}^{-2}$: $+2 + (-2) = 0$, charge balance in 1:1 ratio.
• c. $\text{Cl}^{-}$: Need 2 $\text{Cl}^{-}$ to balance $\text{Ca}^{+2}$, ratio 1:2.
• d. $\text{Na}^{+}$: Both positive, no neutral compound.

Answer:

b. O⁻²