I want to know the answer to the following question:
What is the color of U4+?
All the background I'm provided with is that "The most common ionic forms are U3+ (brown-red), U4+ (green), UO+_2 (unstable), and UO2+_2 (yellow), for U(III), U(IV), U(V), and U(VI), respectively.". Is that enough to answer the question?
Answer: yes