$[$A$]$ Which of the following are invalid variable names and why?

BASICSALARY $\_$basic basic$-$hra

#MEAN group. $422$

population in $2006$ over time mindovermatter

FLOAT hELLO queue.

team$$svictory Plot # $32015\_$DDay

$[$B$]$ Point out the errors, if any, in the following C statements:

$($a$)$ int $=314\mathrm{.}562*150$ ;

$($b$)$ name $=$Ajay$$ ;

$($c$)$ varchar $=3$ ;

$($d$)3\mathrm{.}14*$ r $*$ r $*$ h $=$ vol$\_$of$\_$cyl ;

$($e$)$ k $=($ a $*$ b $)($ c $+(2\mathrm{.}5$a $+$ b $)($ d $+$ e $)$ ;

$($f$)$ m$\_$inst $=$ rate of interest $*$ amo