Answer is (3) both mass number and atomic number.
The notation is ₅₅¹³⁷Cs. The Cs represents the chemical symbol of Caesium element. The subscript number at the left hand side of the symbol indicates the atomic number. Hence, atomic number of Cs is 55. The superscript number at the left hand side of the symbol shows the mass number. Hence, the mass number of the Cs is 137.
<h2>Answer:</h2>
B) endothermic reaction.
<h2>Explanation:</h2>
Melting of ice is endothermic because it is taking heat from the environment, feeling cold, because it requires energy to break the ice bonds. It's also why you feel cold when wet it takes energy to evaporate water. The ice absorbs the energy from the environment. Its internal potential energy increases, therefore, it's endothermic. It also increases the entropy of reaction.
Explanation:
B. HCIO these is the answer
Answer:

Explanation:
Half time is period required to desintegrating the half of the initial number of atoms. Then, the total time is:


The empirical formula of benzene is CH