Explanation:
An alpha particles is basically a helium nucleus and it contains 2 protons and 2 neutrons.
Symbol of an alpha particle is [tex]^{4}_{2}\alpha[/tex].
A beta particle is a particle with a negatively charged electron. Symbol of a beta particle is [tex]^{0}_{-1}\beta[/tex].
According to the given question, the decay series chart along with reaction equation are as follows.
(a) Lead-214 changes to bismuth-214.
[tex]^{214}_{82}Pb \rightarrow ^{214}_{83}Bi + ^{0}_{-1}e[/tex]
(b) Bismuth-214 changes to polonium-214.
[tex]^{214}_{83}Bi \rightarrow ^{214}_{84}Po + ^{0}_{-1}e[/tex]
(c) Polonium-214 changes to lead-210.
[tex]^{214}_{84}Po \rightarrow ^{210}_{82} + ^{4}_{2}He[/tex]
Therefore, we can conclude that proper order of nuclear particle emission is beta, beta, alpha.