Question

1. how many protons, electrons, and neutrons does a neutral atom with atomic number 50 and mass number 125 contain?

a) 50 protons, 50 electrons, 75 neutrons
b) 75 electrons, 50 protons, 50 neutrons
c) 120 neutrons, 50 protons, 75 electrons
d) 70 neutrons, 75 protons, 50 electrons

Explanation:

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<reasoning>

Determine protons and electrons from atomic number

\[

$$\begin{aligned} &\text{Atomic Number } (Z) = 50 \\ &\text{Protons } (p) = Z = 50 \\ &\text{Electrons } (e) = p = 50 \quad (\text{since the atom is neutral}) \end{aligned}$$

\]

Calculate neutrons from mass number

\[

$$\begin{aligned} &\text{Mass Number } (A) = 125 \\ &\text{Neutrons } (n) = A - Z = 125 - 50 = 75 \end{aligned}$$

\]

Match with the correct option

\[
\text{Result: } 50 \text{ protons}, 50 \text{ electrons}, 75 \text{ neutrons} \implies \text{Option A}
\]
</reasoning>

<answer>
<mcq-correct>A) 50 protons, 50 electrons, 75 neutrons</mcq-correct>
<mcq-option>B) 75 electrons, 50 protons, 50 neutrons</mcq-option>
<mcq-option>C) 120 neutrons, 50 protons, 75 electrons</mcq-option>
<mcq-option>D) 70 neutrons, 75 protons, 50 electrons</mcq-option>
</answer>

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Answer:

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<reasoning>

Determine protons and electrons from atomic number

\[

$$\begin{aligned} &\text{Atomic Number } (Z) = 50 \\ &\text{Protons } (p) = Z = 50 \\ &\text{Electrons } (e) = p = 50 \quad (\text{since the atom is neutral}) \end{aligned}$$

\]

Calculate neutrons from mass number

\[

$$\begin{aligned} &\text{Mass Number } (A) = 125 \\ &\text{Neutrons } (n) = A - Z = 125 - 50 = 75 \end{aligned}$$

\]

Match with the correct option

\[
\text{Result: } 50 \text{ protons}, 50 \text{ electrons}, 75 \text{ neutrons} \implies \text{Option A}
\]
</reasoning>

<answer>
<mcq-correct>A) 50 protons, 50 electrons, 75 neutrons</mcq-correct>
<mcq-option>B) 75 electrons, 50 protons, 50 neutrons</mcq-option>
<mcq-option>C) 120 neutrons, 50 protons, 75 electrons</mcq-option>
<mcq-option>D) 70 neutrons, 75 protons, 50 electrons</mcq-option>
</answer>

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