What is true when transient equilibrium occurs between 99Mo and 99mTc?

Transient equilibrium occurs when two radioisotopes are in a relationship where one is a parent and the other is its daughter. In this case, 99Mo decays to produce 99mTc, and during transient equilibrium, the activity of the daughter isotope (99mTc) will increase and eventually reach a level where it is comparable to the activity of the parent isotope (99Mo). However, their activities will not be equal; rather, a consistent ratio exists between them that reflects their respective decay constants.

When transient equilibrium is established, the activity of 99mTc, the daughter, rises until it reaches a point where its rate of production (from the decay of 99Mo) matches its rate of decay. This leads to a constant ratio of their activities over time. As time progresses, as long as enough parent material remains, this ratio will stay constant, which is characteristic of transient equilibrium.

The other options do not accurately reflect the concept of transient equilibrium. Activities are not equal, 99mTc may not necessarily be at its maximum activity during this state, and the decay constants for 99Mo and 99mTc are different; 99Mo has a much longer half-life compared to the shorter half-life of