Question

Chemists have determined that elements with atomic numbers greater than 92 are all

radioactive. In general, their half-lives are much shorter than the age of the universe. This
means that they no longer exist in nature and have all been artificially produced by
scientists in nuclear reactions.
Elements 93 through 105 in the periodic table have been created and named, and
scientists have claimed discovery of elements 106 and 107. The transuranium elements,
as they are called, become less stable as the atomic number and mass increase. For
example, element number 93, neptunium, has a half-life of two million years, while
element number 104, kurchatovium, has a half-life of 70 seconds.
The transuranium elements are the heaviest elements that exist and are readily
fissionable when subjected to nuclear bombardment. Chemists studying these elements
and the periodic table predict that stable elements may be found around atomic numbers
114 or 126.
Based on the information in the passage, which of the following relationships appears to
be true for those elements 93 through 105?
A. The greater the half-life, the greater the radioactivity.
B. The greater the atomic number, the greater the element stability.
C. The greater the radioactivity, the greater the half-life.
OD. The greater the atomic number, the lower the half-life.
OE. The greater the atomic number, the higher the half-life.

Answer 1

The correct relationship is D. The greater the atomic number, the lower the half-life.

The passage states that the transuranium elements, elements with atomic numbers greater than 92, have short half-lives and become less stable as the atomic number and mass increase. It also gives specific examples of the half-lives of neptunium (element 93) and kurchatovium (element 104) to support this claim. Thus, as the atomic number increases, the half-life of the element decreases.