3. (5 points) A 200.0 g piece of iron at 250 .C' is submerged in 1.4 kg of water at 8.0' C' to be cooled. The specific heat capacity of water is 4184 J kg C and the specific heat capacity of iron is 450 J kg-1 C-1. Determine the final temperature of the iron and water.4. (5 points) After the accident in Chernobyl, a radiation detector measured the activity of the Cesium-137 isotope to be 2.0 x 104 Bq. Cesium-137 has a half-life of thirty years. If a "safe" amount of radiation is roughly 155 Bq, how many years will it be before Cesium-137 returns to acceptable levels