Sure, let's solve the problem step-by-step.
We are given the atomic numbers and atomic masses of certain elements, and we need to identify which elements have an atomic number less than 60 and an atomic mass greater than 135.6 u. Here is the data provided:
1. Cesium (Cs) - Atomic Number: 55, Atomic Mass: 132.91 u
2. Barium (Ba) - Atomic Number: 56, Atomic Mass: 137.33 u
3. Cerium (Ce) - Atomic Number: 58, Atomic Mass: 140.1 u
4. Praseodymium (Pr) - Atomic Number: 59, Atomic Mass: 140.91 u
Now, we apply the given conditions:
1. Cesium (Cs):
- Atomic Number: 55 (less than 60)
- Atomic Mass: 132.91 u (not greater than 135.6 u)
- Does not satisfy both conditions
2. Barium (Ba):
- Atomic Number: 56 (less than 60)
- Atomic Mass: 137.33 u (greater than 135.6 u)
- Satisfies both conditions
3. Cerium (Ce):
- Atomic Number: 58 (less than 60)
- Atomic Mass: 140.1 u (greater than 135.6 u)
- Satisfies both conditions
4. Praseodymium (Pr):
- Atomic Number: 59 (less than 60)
- Atomic Mass: 140.91 u (greater than 135.6 u)
- Satisfies both conditions
Based on our conditions, the symbols for the chemical elements that have an atomic number less than 60 and an atomic mass greater than 135.6 u are:
- Barium (Ba)
- Cerium (Ce)
- Praseodymium (Pr)
Therefore, the symbols for these elements are:
- Ba
- Ce
- Pr
