Which of the infrared spectra is that of butanone and which one is of butan-$2$-ol? 

Name the following compound:

${\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{CH}}_2\mathrm{OH}$

Draw the skeletal formulae of :

pentan-$2$-one

Ethanol can be made from ethanal using sodium tetrahydridoborate (III) as a reducing agent. The reaction mechanism proceeds in a similar way to the steps in the reaction of ethanal with $\mathrm{HCN}$, but the initial attack is by the ${\mathrm{H}}^{+}$ion instead of the ${\mathrm{CN}}^{-}$ion. The intermediate then gains an ${\mathrm{H}}^{+}$ion from a water molecule to form the product, ethanol.

Using your knowledge of the reaction between ethanal and $\mathrm{HCN}$, suggest the name of the mechanism to reduce ethanal. Then describe the mechanism as fully as you can, using curly arrows to show the movement of electron pairs.