Question

Arrange the following in increasing order of surface tension. I(water), II(ethanol), III(hexane)

• A. I < II < III
• B. II < I < III
• C. III < I < II
• D. III < II < I

Answer 1

The correct option is D III < II < I

As intermoleular force of attraction increases, surface tension also increases. Hexane has weaK van der Waals forces of attraction, so it has least intermolecular forces of attraction thus, least value of surface tension. Whereas water and ethanol has hydrogen bonding hence their surface tension is greater than hexane molecules. Water has stronger H-bonding than ethanol. So water has maximum force of attraction, hence maximum surface tension i.e. ${\gamma }_{\left(water\right)}>{\gamma }_{\left(ethanol\right)}$