A clock with an iron pendulum keeps correct time at  150C. If the coefficient of linear expansion of iron is  0.000012/0C and the room temperature is 200C  it loses time in a day in seconds is

loss or gain of time by clock per day is ΔT=12αΔt×86400 second here α is coefficient of linear expansion=12x10−6/C  0;Δt is change in temperature =5C  0 ΔT=12×12×10−6×5×86400 ΔT=3×864×10−3 ΔT=2592×10−3=2.592≃2.6 seconds=time lost in a day