question_answer

A liquid\[X\]of density\[3.36g/c{{m}^{2}}\]is poured in a \[U-\]tube, which contains Hg. Another liquid Y is poured in left arm with height 8 cm, upper levels of\[X\]and Y are same. What is density of Y?

A)  0.8g/cc                                

B)  1.2g/cc

C)  1.4 g/cc                               

D)  1.6 g/cc

Correct Answer: A

Solution :

                 As shown in figure, in the two arms of a tube pressure remains same on surface PP'. Hence, \[8\times {{\rho }_{\gamma }}\times g+2\times {{\rho }_{Hg}}\times g=10\times {{\rho }_{\gamma }}\times g\] \[\therefore \] \[8{{\rho }_{\gamma }}+2\times 13.6=10\times 3.36\] Or           \[{{\rho }_{\gamma }}=\frac{33.6-27.2}{8}=0.8\,g/cc\]