1. Sodium-24 has a half-life of 15 hours. How much sodium-24 will remain in an 26.0 g sample after 60 hours?

1.625g

Explanation:

The half - life of a radioactive substance is the time taken for half of it to decay to half of its original composition.

 For the given specie, the original composition is 26g  and the half life is 15hrs:

                At time 0hrs                    Mass  = 26g

For the first half life at time 15hrs         Mass  = 13g

                                             30hrs        Mass  = 6.5g

                                              45hrs        Mass = 3.25g

                                              60hrs        Mass  = 1.625g

1.195000

explanation:

total mass=0.0117+0.0137+0.0881+0.0111

total mass= 0.01172kg

total velocity = 0.283-0.743+0.871-0.799+0.155+0.637+0.301=0.102

momentum=mv=0.1172*0.102=1.195000//