Question

question 10 of 10 which nucleus completes the following equation? (_{92}^{239}u
ightarrow _{ - 1}^{0}e+?) a. (_{91}^{239}pa) b. (_{93}^{240}np) c. (_{93}^{239}np) d. (_{91}^{238}pa)

Explanation:

Step1: Apply conservation of mass - number

In a nuclear - decay equation, the sum of mass - numbers on the left - hand side must equal the sum of mass - numbers on the right - hand side. The mass - number of \(^{239}_{92}U\) is 239 and the mass - number of \(^{0}_{ - 1}e\) is 0. Let the mass - number of the unknown nucleus be \(A\). Then \(239=0 + A\), so \(A = 239\).

Step2: Apply conservation of atomic - number

The sum of atomic numbers on the left - hand side must equal the sum of atomic numbers on the right - hand side. The atomic number of \(^{239}_{92}U\) is 92 and the atomic number of \(^{0}_{ - 1}e\) is - 1. Let the atomic number of the unknown nucleus be \(Z\). Then \(92=-1 + Z\), so \(Z = 93\).

Step3: Identify the element

The element with atomic number \(Z = 93\) is neptunium (\(Np\)). So the unknown nucleus is \(^{239}_{93}Np\).

Answer:

C. \(^{239}_{93}Np\)