Using figur

Boiling point of methyl alcohol at 1atm is 65 and at 0.5 atm is 48.

Explanation

To find the boiling point from above figure, we must look for the temperature on x-axis corresponding to pressures given in question.

So, for first pressure i.e. 1atm=760mm of Hg, the corresponding temperature on x- axis is 65. This shown by yellow line in figure.

For the second pressure i.e. 0.5 atm

1atm=760mm of Hg

0.5atm =7600.5 mm of Hg= 375mm of Hg

For 375mm of Hg the corresponding temperature on x-axis is 48. This is shown by orange line in the figure.