$0.535gm$ of ethanol and acetaldehyde mixture when heated with Fehling's solution gave $1.2gm$ of red precipitate. If ‘x’ is the percentage of acetaldehyde in the mixture, then find the value of x=________ (nearest integer)
(At weight of Cu=63.5,O=16,C=12)
 

$C_2{H}_{5}OH+C{H}_{3}CHO=0.535gm$

Let ‘a’ gm $C_2{H}_{5}OH$  and ‘b’ gm  $C{H}_{3}CHO$  be present in mixture

$\therefore a+b=0.535$

Now, mixture react with Fehling’s solution to give a red precipitate

$\because 143.6gmC{u}_{2}O$  is given by 44gm  $C{H}_{3}CHO$

$\therefore 1.2gmofC{u}_{2}O$  is given by ? 

$=\frac{44\times 1.2}{143.6}=0.368gmC{H}_{3}CHO$

$\therefore b=0.368gm$

$\therefore \% of \therefore \%ofC{H}_{3}CHO=\frac{0.368}{0.535}\times 100=68.73\%$