Question

Can someone explain #3

Answer 1

See below.

Step-by-step explanation:

121.76 amu is the Relative Atomic Mass of Antimony (the average mass of the different isotopes). . The element exists as a mixture of isotopes , the main one being SB121 which has a mass of 121.

Answer 2

Step-by-step explanation:

Hey,

so here the student is saying that the given mass is of one atom. But when we usually talk about amu it is the unified atomic mass so mass of all the atoms present.

So that's why he is wrong.

Also the definitions states,

The atomic mass of an element is the average mass of the atoms of an element measured in atomic mass unit (amu, also known as daltons, D). The atomic mass is a weighted average of all of the isotopes of that element, in which the mass of each isotope is multiplied by the abundance of that particular isotope.