Which of the following is a fossil pteridophyte?

Which one of the following conditions is incorrect for a well-behaved wave function $(\psi)$?

Two electric charges of $9 \mu C$ and $-3 \mu C$ are placed $0.16 \ m$ apart in air. There will be a point $P$ on the line joining the two charges and in between them where the electric potential is zero. The distance of $P$ from the $9 \mu C$ charge is (in $m$)

Observe the following statements :
$I$. The circle $x^2+y^2-6x-4y-7=0$ touches the $y$-axis.
$II$. The circle $x^2+y^2+6x+4y-7=0$ touches the $x$-axis.
Which of the following is a correct statement?

If the area bounded by $y = ax^2$ and $x = ay^2$ for $a > 0$ is $1$,then $a =$

$A$ transistor is used as an amplifier in $CB$ mode with a load resistance of $5 \; k\Omega$. The current gain of the amplifier is $0.98$ and the input resistance is $70 \; \Omega$. The voltage gain and power gain respectively are: