Ascientist has found two samples of radioactive material. the first sample has a mass of 1.0 g and an activity of 2.0 mc022-1.jpg 109 decays per second (d/s). the second sample has an activity of 3.0 mc022-2.jpg 109 d/s. according to the curies’ findings, what is the mass of the second sample?
1.0 g1.5 g5.0 109 g6.0 1018 g

Two nitro no2 groups are chemically bonded to a patch of surface. they can't move to another location on the surface, but they can rotate (see sketch at right). it turns out that the amount of rotational kinetic energy each no2 group can have is required to be a multiple of ε, where =ε×1.010−24 j. in other words, each no2 group could have ε of rotational kinetic energy, or 2ε, or 3ε, and so forth — but it cannot have just any old amount of rotational kinetic energy. suppose the total rotational kinetic energy in this system is initially known to be 32ε. then, some heat is removed from the system, and the total rotational kinetic energy falls to 18ε. calculate the change in entropy. round your answer to 3 significant digits, and be sure it has the correct unit symbol.

In a heat engine of 1000 j of heat enters the system and the piston does 500 j of work what is the final internal energy of the system if the inital energy was 2000 j we have to do all of these down here 1)write the equation 2)list out your know variables 3)plug the numbers into the equations 4)solve 5)write your solution statemtn that includes inital energuy and final energuy added

Reactions in cells take place at about a. 40°c b. 0° c. 100°c d. 60°c