Which of the following is a correctly balanced nuclear reaction?A) 92238 U → 90232 Th + 24 HeB) 98249 Cf + 715 N → 105260 Db + 3 01 nC) 12 H + 13 H → 24 He + 2 01 nD) 92238 U + 01 n → 92239 UE) 1940 K → 2040 Ca + +10β

To balance a nuclear reaction, the sum of the atomic numbers (the superscripts) and the sum of the atomic masses (the subscripts) must be the same on both sides of the equation.

Let's check each option:

A) 92238 U → 90232 Th + 24 He The atomic numbers (92 vs 90+2) and atomic masses (238 vs 232+4) are balanced, so this reaction is correctly balanced.

B) 98249 Cf + 715 N → 105260 Db + 3 01 n The atomic numbers (98+7 vs 105+0) and atomic masses (249+15 vs 260+3) are not balanced, so this reaction is not correctly balanced.

C) 12 H + 13 H → 24 He + 2 01 n The atomic numbers (1+1 vs 2+0) and atomic masses (2+3 vs 4+2) are balanced, so this reaction is correctly balanced.

D) 92238 U + 01 n → 92239 U The atomic numbers (92+0 vs 92+0) and atomic masses (238+1 vs 239) are balanced, so this reaction is correctly balanced.

E) 1940 K → 2040 Ca + +10β The atomic numbers (19 vs 20+(-1)) and atomic masses (40 vs 40+0) are not balanced, so this reaction is not correctly balanced.

So, the correctly balanced nuclear reactions are A, C, and D.