What will be the length (in cm) of mercury column in a barometer tube, when the atmospheric pressure is 75 cm of mercury and the tube is inclined at an angle of 600 to the  vertical?

Let l be length of the mercury column in the barometer tube. As the barometer tube is inclined at an angle of 60o to the vertical, effective height (vertical) of the mercury column = l cos 60o. Since atmospheric pressure is 75 cm of mercury column, /cos 600=75 or l=75cos⁡60∘=751/2=150cm