Answer
(a)$^{238}_{92}U$ uranium
(b) $^{24}_{12}Mg$ magnesium
(c)$^{13}_{6}C$ carbon
Work Step by Step
(a)
in $\alpha $ deacy
$^{A}_{Z}P$ $\longrightarrow$ $^{A-4}_{Z-2}D+^{4}_{2}He$
Here $P$ is parent nucleus, $D$ is daughter nucleus and $^{0}_{-1}e$ is positron or $\beta^{-}$ particle
$^{242}_{94}Pu$ $\longrightarrow$ $^{238}_{92}U+^{4}_{2}He$
(b)
in $\beta^{-}$ deacy
$^{A}_{Z}P$ $\longrightarrow$ $^{A}_{Z+1}D+^{0}_{-1}e$
Here $P$ is parent nucleus, $D$ is daughter nucleus and $^{0}_{-1}e$ is positron or $\beta^{-}$ particle
$^{24}_{11}Na$ $\longrightarrow$ $^{24}_{12}Mg+^{0}_{-1}e$
(c)
in $\beta^{+}$ deacy
$^{A}_{Z}P$ $\longrightarrow$ $^{A}_{Z-1}D+^{0}_{+1}e$
Here $P$ is parent nucleus,$D$ is daughter nucleus and $^{0}_{+1}e$ is positron or $\beta^{+}$ particle
$^{13}_{7}N$ $\longrightarrow$ $^{13}_{6}C+^{0}_{+1}e$
