Answer
a) $^{222}_{86}Rn$ -> $^{218}_{84}Po + ^{4}_{2}He$
b) $^{234}_{90}Rn$ -> $^{230}_{88}Po + ^{4}_{2}He$
c) $^{210}_{84}Rn$ -> $^{206}_{82}Pb + ^{4}_{2}He$
Work Step by Step
a) $^{222}_{86}Rn$ -> $^{218}_{84}Po + ^{4}_{2}He$
b) $^{234}_{90}Rn$ -> $^{230}_{88}Po + ^{4}_{2}He$
c) $^{210}_{84}Rn$ -> $^{206}_{82}Pb + ^{4}_{2}He$