A new element was discovered. It’s average atomic mass was found to be 245.6 amu. Isotope #1 has a mass of 243.2 amu; isotope #2 has a mass of 244.9 amu; isotope #3 has a mass of 247.2 amu. Which isotope is most likely to be the most abundant? A
Isotope 1

B
Isotope 2

C
Isotope 3

D
They all contribute the same amount

B. Isotope 2

Explanation:

Isotopes can be defined as the atom of an element that has the same number of protons but different number of neutrons. This ultimately implies that, the isotopes of an element have the same atomic number (number of protons) but different atomic mass (number of nucleons).

Basically, the atomic mass of any chemical element found in the periodic table is equal to the weighted average of all its isotopes. Therefore, the isotope with the closest mass to the weighted average would be the most abundant.

In this scenario, a new element was discovered with an average atomic mass of 245.6 amu.

Hence, the isotope which is most likely to be the most abundant is isotope #2 that has a mass of 244.9 amu because it is closest in mass to the relative atomic mass (weighted average) of 245.6 amu.

if you're asking what comes out, it's steam.

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.