Acid hydrolysis of $X$ yields two different organic compounds. Which one of the following is $X$?

The correct order of acid strength of the following carboxylic acids is $-$

An organic compound having molecular formula $C_2H_6O$ undergoes oxidation with $K_2Cr_2O_7 / H_2SO_4$ to produce $X$ which contains $40\,\%$ carbon,$6.7\,\%$ hydrogen and $53.3\,\%$ oxygen. The molecular formula of the compound $X$ is

Calculate the value of $x + \text{molecular mass of } (C)$,where $x$ is the number of moles of $PhMgBr$ consumed in reaction $(a)$ and $(C)$ is the gas evolved in reaction $(b)$.
$(a)$ $3\text{-hydroxy-5-formylbenzoyl chloride} + x \ PhMgBr \xrightarrow{\text{excess}} (A)$
$(b)$ $2,5\text{-dioxocyclohexanecarboxylic acid} \xrightarrow{\Delta} (B) + (C) \uparrow$

Which of the following has highly acidic hydrogen?

$CH_3-CO-CH_2-COOC_2H_5 \xrightarrow{NaOH, H_2O} A$. The product '$A$' in the reaction is