Question

Thallium consists of 29.5%TI-203 and 70.5%TI-205. What is the relative atomic mass of thallium?

Answer 1

Answer:

B. 204 amu

Explanation:

Given:

Isotopes of Thallium and % abundances

Tl-203 : 29.5%

Tl-205: 70.5%

Formula:

Relative atomic mass = $\sum (Isotope mass * abundance)/100$

It is given by the summation of the product of all the isotope masses and their % abundances

For Thallium:

Relative atomic mass = $[203*29.5 + 205*70.5]/100 = 204.41 amu$

Since the number of significant digits is 3, the relative atomic mass = 204 amu

Answer 2

E. 204.4 hope this helps