Ice starts freezing in a lake with water at 0°C when the atmospheric temperature is −10∘C.  If the time taken for 1 cm of ice to be formed is 12 minutes, the time taken for the thickness of the ice to change from 1 cm to 2 cm will be:

Time taken by ice to grow a thickness y,t=ρL2Kθy2Hence, time intervals to change thickness from 0 to y, from y to 2y and soon will be in the ratioΔt1:Δt2:::12−02:22-12 or Δt1:Δt2::1:3According to question,Δt1=12 minutes Hence,Δt2=3Δt1=3×12min=36min