Question

question 13
a compound contains an unknown ion x and has the formula xo₂. ion x contains 78 electrons. what is ion x?
sn⁴⁺
fe²⁺
sn²⁺
pb⁴⁺

question 14
1 pts
which of the following correctly represents a common oxyanion and its charge: (pick all the apply)
clo₃⁻
so₃²⁻
no₃⁻
co₃²⁻
so₄²⁻
po₄³⁻

Explanation:

Step1: Determine charge of X in $XO_2$

Oxygen in compounds usually has a - 2 charge. In $XO_2$, let the charge of X be $n$. Then $n+2\times(- 2)=0$ (since the compound is neutral), so $n = + 4$.

Step2: Find the number of electrons in neutral atoms of the elements

• Sn (tin): Atomic number of Sn is 50. For $Sn^{4+}$, the number of electrons is $50 - 4=46$.
• Fe (iron): Atomic number of Fe is 26. For $Fe^{2+}$, the number of electrons is $26 - 2 = 24$.
• Sn (again): For $Sn^{2+}$, the number of electrons is $50-2 = 48$.
• Pb (lead): Atomic number of Pb is 82. For $Pb^{4+}$, the number of electrons is $82 - 4=78$.

Step3: Identify the ion X

Since the ion X has 78 electrons and a + 4 charge, the ion is $Pb^{4+}$.

Step4: Recall common oxyanions and their charges

• $ClO_2^{-}$ has a - 1 charge, not - 3.
• $SO_3^{2 - }$ is sulfite ion with a - 2 charge.
• $NO_3^{-}$ is nitrate ion with a - 1 charge.
• $CO_3^{2 - }$ is carbonate ion with a - 2 charge.
• $SO_4^{2 - }$ is sulfate ion with a - 2 charge.
• $PO_4^{3 - }$ is phosphate ion with a - 3 charge.

Answer:

Question 13: D. $Pb^{4+}$
Question 14: B. $SO_3^{2 - }$, C. $NO_3^{-}$, D. $CO_3^{2 - }$, E. $SO_4^{2 - }$, F. $PO_4^{3 - }$