Correct Answer - D
These are acid-base reactions. Acid-base reactions always go from the stronger acids and bases to the weaker ones. Therefore, actylene (an acid) will only react with bases that are converted to acids weaker than acetylene, and acetylide ion (a base) will only react with acids that are converted to bases weaker than acetylide ion:
`HCNgtCH_3OHgtC_2H_2gtH_2=CH_4`
`underset("Stronger base")(HC-=CNa)+underset("Stronger acid")(CH_3OH)tounderset("weaker acid")(CH-=CH)+underset("Weaker base")(CH_3ONa)`
`underset("Stronger acid")(HC-=CH)+underset("Stronger base")(CH_3Li)tounderset("Weaker base")(HC-=CLi)+underset("Weaker acid")(CH_4)`
`underset("Stronger acid")(HC-=CH)+underset("stronger base")(NaH)tounderset("Weaker base")(HC-=CNa)+underset("Weaker acid")(H_2)`
`HC-=CH+NaCNto` No reaction.
HCN is a stronger acid than acetylene, thus, weaker acid acetylene cannot displace stronger acid HCN from its salt.
