Question

what type of reaction is the generic equation: ab + cd → ad +cb
○ decomposition
○ synthesis or combination
○ single replacement/displacement
○ double replacement/displacement
question 54 (0.0862 points)
which of the following species has the electron configuration of $1s^2 2s^2 2p^6 3s^2 3p^6$
○ $\text{cl}^-$
○ $\text{o}^{2-}$
○ $\text{na}^+$
○ all of these

Explanation:

First Question (Reaction Type):

To determine the reaction type, we analyze the generic equation \( AB + CD
ightarrow AD + CB \). In a double replacement reaction, the cations and anions of two compounds exchange places. Here, \( A \) and \( C \) (cations) swap with \( B \) and \( D \) (anions), matching the double replacement pattern. Decomposition is \( AB
ightarrow A + B \), synthesis is \( A + B
ightarrow AB \), and single replacement is \( A + BC
ightarrow AC + B \), so these don't fit.

The electron configuration \( 1s^2 2s^2 2p^6 3s^2 3p^6 \) has 18 electrons. \( \text{Cl}^- \) is \( \text{Cl} \) (17 electrons) plus 1, so 18. \( \text{O}^{2-} \) is \( \text{O} \) (8 electrons) plus 2, so 10. \( \text{Na}^+ \) is \( \text{Na} \) (11 electrons) minus 1, so 10. Only \( \text{Cl}^- \) has 18 electrons, matching the configuration.

Answer:

double replacement/displacement (the option with this text)

Second Question (Electron Configuration):