Решаем по порядку:
\[ {}_3^7Li + {}_1^1H \to {}_2^4He + {}_2^4He \]
\[ {}_{84}^{211}Po + {}_0^1n \to {}_{82}^{208}Pb + {}_2^4He \]
\[ {}_{25}^{55}Mn + {}_1^1H \to {}_{26}^{56}Fe + {}_0^0\gamma \]
\[ {}_{19}^{41}K + {}_2^4He \to {}_{20}^{44}Ca + {}_1^1H \]
Ответ: \[ {}_3^7Li + {}_1^1H \to {}_2^4He + {}_2^4He \], \[ {}_{84}^{211}Po + {}_0^1n \to {}_{82}^{208}Pb + {}_2^4He \], \[ {}_{25}^{55}Mn + {}_1^1H \to {}_{26}^{56}Fe + {}_0^0\gamma \], \[ {}_{19}^{41}K + {}_2^4He \to {}_{20}^{44}Ca + {}_1^1H \]