Two vessels of different materials are similar in size in every respect. The same quantity of ice filled in them gets melted in 20 minutes and 30 minutes. The ratio of their thermal conductivities will be

Two vessels of different materials are similar in size in every respect. The same quantity of ice filled in them gets melted in 20 minutes and 35 minutes respectively. The ratio of the thermal conductivities of their materials is

Two vessels of different materials are similar in size in every respect. The same quantity of ice filled in them gets melted in 20 minutes and 40 minutes respectively. The ratio of thermal conductivities of the materials is

Two vessels of different materials are similar in size in every respect. The same quantity of ice filled in them gets melted in 20 minutes and 40 minutes respectively. The ratio of thermal conductivities of the metals is

Two vessels of different materials are similar in size in every respect. The same quantity of ice filled in them gets melted in 20 min. and 40 min respectively. The ratio of their thermal conductivity is

Two vessels of different materials are similar in size in every respect. The same quantity of ice filled in them gets melted in 20 min and 35 min, respectively. The ratio of coefficients of thermal conduction of the metals is

Two vessels made of different materials are identical in all respects. The same quantity of Ice filled in them gets melted in 27 min. and 45 min. when placed in same surroundings. If thermal conductivity of material of 1st vessel is 180wm^(-1)k^(-1) , then Thermal conductivity of material of second vessel will be