• A. $CO$
• B. $C{O}_2$
• C. $S_{2}O$
• D. $CFC$

Answer: Option B

Explanation:

• A. $RCC$
• B. $RCB$
• C. $RCCUB$
• D. $R\subset C\times B$

Answer: Option D

Explanation:

• A. $C{a}^{++}$
• B. $C{u}^{++}$
• C. $N{a}^{+}$
• D. $K^{+}$

Answer: Option A

Explanation: