Question

question 7 the impossible isotope is because a. $_1^1h$ b. $_{95}^{241}am$ c. $_{9}^{4}be$ d. $_1^2h$

Explanation:

Step1: Recall isotope notation rules

Isotope notation is $_{Z}^{A}X$, where $A$ (mass - number) is the sum of protons and neutrons and $Z$ (atomic number) is the number of protons. Also, $A\geq Z$ and $Z$ is a non - negative integer equal to the position of the element in the periodic table.

Step2: Analyze option C

For $_{9}^{4}Be$, the atomic number of beryllium ($Be$) is $Z = 4$, but here the mass number $A=4$. Since the number of neutrons $N=A - Z$, and $A = Z$ in this case, there are no neutrons. Also, the notation has the atomic number and mass number swapped. The correct notation for a beryllium isotope should have the atomic number as the lower sub - script and mass number as the upper superscript. In addition, a mass number of 4 for beryllium is not possible as the most common and stable isotope of beryllium is $_{4}^{9}Be$.

Step3: Analyze option A

$_{1}^{1}H$ is hydrogen - 1 (protium), a common isotope of hydrogen with 1 proton and 0 neutrons.

Step4: Analyze option B

$_{95}^{241}Am$ is americium - 241, an isotope of americium with atomic number 95 and mass number 241.

Step5: Analyze option D

$_{1}^{2}H$ is deuterium, an isotope of hydrogen with 1 proton and 1 neutron.

Answer:

C. $_{9}^{4}Be$ because the atomic number and mass number are in the wrong positions and a mass number of 4 for beryllium is not possible.