Question

The reactions listed below are either chemical reactions or nuclear reactions. Which are nuclear reactions? Check all that apply.

Upper H superscript plus, plus upper O upper H superscript minus right arrow upper H subscript 2 upper O.

Superscript 185 subscript 79 upper A u right arrow superscript 181 subscript 77 upper R d plus superscript 4 subscript 2 upper H e.

4 upper F e plus 3 upper O subscript 2 right arrow 2 upper F e subscript 2 upper O subscript 3.

Superscript 210 subscript 84 upper P o right arrow superscript 206 subscript 82 upper P b plus superscript 4 subscript 2 upper H e.

Answer 1

The nuclear reactions are the 2nd and the 4th.

Reasons:
- 1) H+ + OH− → H2O — chemical (ions combine; no change in nuclei).
- 2) 185/79 Au → 181/77 (Rd) + 4/2 He — nuclear (mass and atomic numbers change; alpha emission).
- 3) 4 Fe + 3 O2 → 2 Fe2O3 — chemical (oxidation; atoms rearrange but nuclei unchanged).
- 4) 210/84 Po → 206/82 Pb + 4/2 He — nuclear (alpha decay; nuclei change).