Question

Assertion: If work done in increasing the size of a soap film from 10 cm x 4 cm to 10 cm x 8 cm is 2 x 10^-4 J, then the surface tension is 5 x 10^-4 N m^-1.

Reason: Work done = Surface tension x increase in area.

विकल्प

• Assertion is True, Reason is True; Reason is a correct explanation for Assertion.

• Assertion is True, Reason is True; Reason is not a correct explanation for Assertion.

• Assertion is True, Reason is False.

• Assertion is False but, Reason is True.

Answer 1

Assertion is False but, Reason is True.

Explanation:

Here, Assertion is false but Reason is true. As work done is,

W = S.T. x increase in area

or S.T

`= "W"/ "increase in area"`

`= (2 xx 10^-4)/((10 xx 8 - 10 xx 4)10^-4`

`= 5 xx 10^-2  "N/m"`