Which of the following species is least likely to act as a Lewis base?

1. F^–
2. BF₃
3. PF₃
4. CO

The strongest acid among the following compounds is:

Find the solubility product (Kₛₚ) of Ba(OH)₂ if the pH of its saturated solution is 12.

Which of the following equimolar solutions, prepared separately, will have the highest pH?

Buffer solutions have constant acidity and alkalinity because:
 

A buffer solution is prepared in which the concentration of NH₃ is 0.30 M and the concentration of  $N{H}_4^{+\hspace{0.17em}}$ is 0.20 M. If the equilibrium constant, K_b for NH₃ equals 1.8×10^–5, then what is the pH of this solution? 
(log 1.8 = 0.25; log 0.67 = –0.176)

1.  9.43
2.  11.72
3.  8.73
4.  9.08

What conditions favor the formation of 2XY₄(g) in the reaction X₂(g) + 4Y₂(g) ⇋ 2XY₄(g), considering that the enthalpy change (ΔH) is negative?

Find the equilibrium constant K for the reaction:

NO₂(g) ⇌ ½N₂(g) + O₂(g)

Given:

N₂(g) + O₂(g) ⇌ 2NO(g), K₁

2NO(g) + O₂(g) ⇌ 2NO₂(g), K₂

A saturated solution of Ba(OH)₂ has a pH of 12. The value of its K_sp will be:
1. $4.00\times {10}^{-6}$ $M^3$
2. $4.00\times {10}^{-7}$ $M^3$
3. $5.00\times {10}^{-6}$ $M^3$
4. $5.00\times {10}^{-7}$ $M^3$

Calculate the hydrogen ion concentration, [\(\text{H}^+\)] (in \(\text{mol}/\text{L}\)), of a buffer solution prepared by mixing \(0.10 \text{ M}\) acetic acid (\(\text{CH}_3\text{COOH}\)) and \(0.20 \text{ M}\) sodium acetate (\(\text{CH}_3\text{COONa}\)), given that the acid dissociation constant (\(\text{K}_a\)) for acetic acid is \(1.8 \times 10^{-5}\):

1. \(3 . 5 \times 10^{- 4}\)
2. \(1 . 1 \times 10^{- 5}\)
3. \(1 . 8 \times 10^{- 5}\)
4. \(9 . 0 \times10^{- 6}\)${\mathrm{}}^{}$