In the given transformation,which of the following is the most appropriate reagent?

Which is the best oxidizing agent to oxidize $CH_3CH=CHCHO$ to $CH_3CH=CHCOOH$?

Given below are two statements:
Statement $I$ : Acidity of $\alpha$-hydrogens of aldehydes and ketones is responsible for Aldol reaction.
Statement $II$ : Reaction between benzaldehyde and ethanal will $NOT$ give Cross-$Aldol$ product.
In the light of above statements,choose the most appropriate answer from the options given below.

$CH_3-C \equiv CH \xrightarrow[dil. H_2SO_4]{Hg^{+2}} (P)$,$CH_3-C \equiv CH \xrightarrow[(2) H_2O_2]{(1) BH_3, THF} (Q)$. $P$ and $Q$ can be differentiated by

How will you convert butan-$2$-one to propanoic acid?
$CH_3-CH_2-CO-CH_3 + I_2 + NaOH$ $\rightarrow C_2H_5CO_2^-Na^+ + CHI_3$ $\xrightarrow{H^+} C_2H_5COOH$

Upon reaction with $CH_3MgBr$ followed by protonation,the compound that produces ethanol is