Water rises to a height of `10 cm` in a capillary tube and mercury falls to a depth of `3.42 cm` in the same capillary tube. If the density of mercury is `13.6 g//c.c.` and the angles of contact for mercury and for water are `135^@` and `0^@`, respectively, the ratio of surface tension for water and mercury is

Options

A. `1:0.15`
B. `1:30`
C. `1:65`
D. `1.5:1`

Answer

C

Explanation

`h=(2Tcostheta)/(rpg)`
or `T=(hrpg)/(2cos theta)`
or `T prop(hp)/(cos theta)`
`(T_(w))/(T_(Hg))=(h_(1))/(h_(2))xx(costheta_(2))/(cos theta_(1))xx(p_(1))/(p_(2))xx(1)/sqrt(2)xx(1)/(13.6)=(1)/(65)`