A mystery element "A" has two stable isotopes X-100 which occurs 20% of the time and X-120 which occurs 80% of the time. What is the average mass of element "A"?

A-100 amu

B-104 amu

C-116 amu

D-120 amu

The big bang nucleosynthesis theory states that elements were produced in the first few minutes of the big bang while elements have their origins in the interiors of stars, forming much later in the history of the universe.

Why is carbon ideal for making different compounds?

Choose an equation that represents an enzyme-catalyzed reaction. (a) enzyme + substrate → enzyme-substrate complex (b) enzyme + substrate ←−→ enzyme + products (c) enzyme + substrate ←−→ enzyme-substrate complex → enzyme + products (d) enzyme + substrate ←−→ enzyme-substrate complex → enzyme-substrate complex + products