Which among the following is $NOT$ a Lewis acid?

Conjugate base for Bronsted acids $H_{2}O$ and $HF$ are

Which of the following is the weakest base?

Which species acts as an acid in the reaction $CH_{3}COOH_{(aq)} + H_{2}O_{(l)} \rightleftharpoons H_{3}O^{+}_{(aq)} + CH_{3}COO^{-}_{(aq)}$?

Given below are two statements,one is labelled as Assertion $A$ and the other is labelled as Reason $R:$
Assertion $A :$ The amphoteric nature of water is explained by using Lewis acid/base concept.
Reason $R :$ Water acts as an acid with $NH_{3}$ and as a base with $H_{2}S$.
In the light of the above statements,choose the correct answer from the options given below:

Lemon and orange juices contain ......... and ......... acids respectively.