Acids, bases and salts; Arrhenius, Bronsted-Lowry and Lewis concepts — NEET & JEE Questions

Question 1 · difficulty L1 · recall

According to the Bronsted-Lowry concept, an acid is a species that

• A. donates a proton
• B. accepts a proton
• C. donates an electron pair
• D. accepts an electron pair only

Question 2 · difficulty L2 · understanding

According to the Arrhenius concept, a base in aqueous solution increases the concentration of

• A. $H^+$
• B. $OH^-$
• C. electrons
• D. neutral salt molecules only

Question 3 · difficulty L2 · understanding

Which species is a Lewis acid?

• A. $BF_3$
• B. $NH_3$
• C. $OH^-$
• D. $H_2O$ acting as a proton acceptor

Question 4 · difficulty L2 · understanding

In the reaction $NH_3+H_2O\rightleftharpoons NH_4^++OH^-$, $NH_3$ acts as

• A. a Bronsted acid
• B. a Bronsted base
• C. an Arrhenius acid
• D. a Lewis acid only

Question 5 · difficulty L3 · application

In the reaction $HCl+H_2O\rightarrow H_3O^++Cl^-$, which pair is a conjugate acid-base pair?

• A. $HCl$ and $Cl^-$
• B. $HCl$ and $H_3O^+$
• C. $H_2O$ and $Cl^-$
• D. $H_3O^+$ and $Cl^-$

Question 6 · difficulty L3 · application

Which species can act as both a Bronsted acid and a Bronsted base?

• A. $HCO_3^-$
• B. $Na^+$
• C. $Cl^-$ only
• D. $CH_4$

Question 7 · difficulty L3 · application

In the Lewis acid-base interaction $BF_3+NH_3\rightarrow F_3B\leftarrow NH_3$, which species donates the electron pair?

• A. $BF_3$
• B. $NH_3$
• C. both equally
• D. neither

Question 8 · difficulty L3 · application

Which statement about $H_2O$ is correct in Bronsted-Lowry reactions?

• A. It can act only as an acid
• B. It can act only as a base
• C. It can act as either acid or base depending on the reaction
• D. It is never involved in proton transfer

Question 9 · difficulty L4 · application

Which substance is a Lewis acid but need not be a Bronsted-Lowry acid?

• A. $BF_3$
• B. $HCl$
• C. $NH_4^+$
• D. $H_3O^+$

Question 10 · difficulty L4 · application

In $H_2PO_4^-+H_2O\rightleftharpoons H_3O^++HPO_4^{2-}$, what role does $H_2PO_4^-$ play?

• A. Bronsted acid
• B. Bronsted base
• C. Lewis acid only with no proton transfer
• D. Neither acid nor base