Question

\(^{234}\)U has 92 protons and 234 nucleons total in its nucleus. It decays by emitting an alpha particle. After the decay it becomes

• A. \(^{232}\)U
• B. \(^{232}\)Pa
• C. \(^{230}\)Th
• D. \(^{230}\)Ra

Hint:

In alpha decay: \(A \to A-4\) and \(Z \to Z-2\).

Answer 1

The Correct Option is C

Step 1: Recall alpha decay rule.
In alpha decay, nucleus emits \(\alpha\) particle \((^{4}_{2}\text{He})\).
So:
Mass number decreases by 4 and atomic number decreases by 2.
Step 2: Apply to \(^{234}_{92}\text{U}\).
After emission:
\[ A' = 234 - 4 = 230 \]
\[ Z' = 92 - 2 = 90 \]
Step 3: Identify element with atomic number 90.
Atomic number 90 corresponds to Thorium (Th).
Step 4: Write final nucleus.
\[ ^{230}_{90}\text{Th} \]
Final Answer:
\[ \boxed{^{230}\text{Th}} \]