Answer:
The answer is B an open system allows energy and mass to move in and out of it
Hope it helps
Yea! what the person underneath me said
The opposite type of reaction (where energy is taken in from the surroundings of a reaction and thus the energy of the reactants is lower than that of the products) is called an endothermic reaction
Answer:

Explanation:
The atomic number (Z) of copper is 29 and this isotope has an atomic mass (A) of 70.
The general symbol for an isotope E is
.
The atomic number is a left subscript, and the atomic mass is a left superscript.
