if the ratio of Uranium 234 to lead-206 in a rock sample is 0.54 to 0.40 what is the age of the rock sample if half life of Uranium 238 is equal to 4.5 *10 ^9 years​

Neils bohr believed that electrons orbited the nucleus in different energy levels, based on strong support from

Consider the reduction reactions and their equilibrium constants. cu+(aq)+e−↽−−⇀cu(s)pb2+(aq)+2e−↽−−⇀pb(s)fe3+(aq)+3e−↽−−⇀fe(=6.2×108=4.0×10−5=9.3×10−3 cu + ( aq ) + e − ↽ − − ⇀ cu ( s ) k =6.2× 10 8 pb 2 + ( aq ) +2 e − ↽ − − ⇀ pb ( s ) k =4.0× 10 − 5 fe 3 + ( aq ) +3 e − ↽ − − ⇀ fe ( s ) k =9.3× 10 − 3 arrange these ions from strongest to weakest oxidizing agent.

How much heat is added if 0.814g of water increase in temperature by 0.351 degree c?