Is each of the following definitions valid or invalid? If any is invalid, explain why

$\backslash$table$[[$Problem$,\backslash$table$[[$Valid or$],[$invalid$?]],$Why?$],[$int ivar;,,$],[$int ${?}^{**}$ iptr $=$ &ivar;,,$],[$int ivar, ${?}^{**}$ iptr $=,,],[$&ivar;,,$],[$float fvar;,,$],[$int $*$iptr $=$ &fvar;,,$],[$int nums$[50],{?}^{**}$ iptr,,$],[=$ nums;,,$],[$int $*$iptr $=$ &ivar;,,$],[$int ivar;,,$]]$