Key Idea According to Lewis concept, "Acids are electron acceptor and bases are electron donor". Since, electron deficient compounds also have an ability to accept electrons, these are regarded as acids. 
Which of the following molecules acts as a Lewis acid?
Held on 30 Apr 2009 · Verified 9 Jul 2026.
(CH3)3 B
(CH3)2O
(CH3)3P
(CH3)3 N
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For the reaction 2SO₂(g) + O₂(g) ⇌ 2SO₃(g), ΔH = -198 kJ. Which condition favours forward reaction?
The unit of rate constant for a first-order reaction is:
The conjugate base of H₂SO₄ is:
Phosphoric acid ionizes in three steps with their ionization constant values $\mathrm{K}_{\mathrm{a}_1}, \mathrm{~K}_{\mathrm{a}_2}$ and $\mathrm{K}_{\mathrm{a}_3}$, respectively, While K is the overall ionization constant. Which of the following statements are true? A. $\log \mathrm{K}=\log \mathrm{K}_{\mathrm{a}_1}+\log \mathrm{K}_{\mathrm{a}_2}+\log \mathrm{K}_{\mathrm{a}_3}$ B. $\mathrm{H}_3 \mathrm{PO}_4$ is a stronger acid than $\mathrm{H}_2 \mathrm{PO}_4^{-}$and $\mathrm{HPO}_4^{2-}$ C. $K_{a_1}\gt K_{a_2}\gt K_{a_3}$ D. $\mathrm{K}_{\mathrm{a}_1}=\frac{\mathrm{K}_{\mathrm{a}_3}+\mathrm{K}_{\mathrm{a}_2}}{2}$ Choose the correct answer from the options given below:
If the half-life $\left(\mathrm{t}_{1 / 2}\right)$ for a first order reaction is 1 minutes, then the time required for $99.9 \%$ completion of the reaction is closest to:
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