B I think sorry if I’m wrong
Following are the chemical elements that have atomic mass greater than 173.5 u and atomic number less than 75.
1. Lutetium
Atomic Number = 71
Atomic Mass = 174.97 u
2. Hafnium
Atomic Number = 72
Atomic Mass = 178.49 u
3. Tantalum
Atomic Number = 73
Atomic Mass = 180.95 u
4. Tungsten
Atomic Number = 74
Atomic Mass = 183.85 u
Answer:
Rubidium is a typical but very reactive member of the series of alkali metals. It is appreciably more reactive than potassium, but less so than caesium, and so would be expected to react more violently with those materials that are hazardous with potassium or sodium.
