Question

The nuclear equation is incomplete.

Superscript 239 Subscript 94 Baseline P u + Superscript 1 Subscript 0 Baseline n yields Superscript 100 Subscript 40 Baseline Z r + blank + 2 Superscript 1 Subscript 0 Baseline n

What particle completes the equation?

Superscript 138 Subscript 54 Baseline X e
Superscript 139 Subscript 54 Baseline X e
Superscript 119 Subscript 54 Baseline X e
Superscript 138 Subscript 52 Baseline T e

Answer 1

Conserve mass and charge.

Initial: A = 239 + 1 = 240, Z = 94 + 0 = 94.
Products: A = 100 + A_x + 2, so 102 + A_x = 240 → A_x = 138.
Z = 40 + Z_x, so 40 + Z_x = 94 → Z_x = 54.

So the missing particle is 138_54 Xe (xenon-138).