given
  initial
     tempereature T1 = 60C =
279 k
     pressure P1 = rho g h1
              Â
volume = V1
        final
     Temperature T2 = 240C=
297 k
              Â
pressure P2 = ro g h2 = rho g *1
     volume V2 = 2V1
from ideal gas equationn
  PV =nRT
                    Â
P1V1/T1 = P2V2/T2
    Â
    Â
         Â
rho *g *h1* V1 /279 = rho* g* 1 *2V1 / 297
     h1/279 = 2/297
              Â
h1 = 2*279 /(297)
              Â
h1 = 1.8787 m
so depth of the lake is 1.8787 m