ธาตุที่มีมวลไอโซโทป 158.925 34(2) ชื่อว่าอะไร
What is the name of the element with isotopic mass of 158.925 34(2)?
df = pd.DataFrame(columns=['element', 'isotopic_mass___u__'])
df[df['isotopic_mass___u__'] == '158.925 34(2)']['element']