[amp_mcq option1=”higher surface tension” option2=”lower surface tension” option3=”surface tension is no criterion” option4=”high density and viscosity” correct=”option2″]
The correct answer is: B. lower surface tension
Surface tension is a property of liquids that causes them to behave as if they have a thin, elastic skin. This is due to the attraction between the molecules of the liquid. The higher the surface tension, the stronger the attraction between the molecules, and the more difficult it is to deform the surface of the liquid.
In a manometer, the liquid is used to measure pressure. The pressure difference between the two arms of the manometer is proportional to the height difference between the two liquid levels. If the surface tension of the liquid is high, it will tend to pull the liquid levels together, making it more difficult to measure the pressure difference.
A lower surface tension will make it easier to measure the pressure difference, so a better liquid combination for a manometer is one having lower surface tension.
Option A is incorrect because a higher surface tension will make it more difficult to measure the pressure difference.
Option C is incorrect because surface tension is a criterion for choosing a liquid for a manometer.
Option D is incorrect because a high density and viscosity will make it more difficult to measure the pressure difference.