Question

what are two limitations of radiometric dating?
dead organisms can reach a point where there is too little radiation left to make an accurate measurement.
an assumption is made regarding the amount of radioactive isotopes in the organism at the time of death.
the rate of decay is not consistent.
radiometric machines are very difficult to calibrate.

Explanation:

1. Over time, in dead organisms, the amount of radioactive material can decay to such low levels that accurate measurement becomes challenging, which is a limitation of radiometric dating.
2. Radiometric dating assumes a known initial amount of radioactive isotopes in the organism at death. If this assumption is wrong, the dating results will be inaccurate. The rate of decay is consistent (it's a fundamental property of radioactive isotopes), and while radiometric machines may have calibration - related issues, the two main theoretical limitations are the low - radiation problem and the assumption about initial isotope amounts.

Answer:

Dead organisms can reach a point where there is too little radiation left to make an accurate measurement.
An assumption is made regarding the amount of radioactive isotopes in the organism at the time of death.