Which of the following compounds is the least ionic?

Which of the following is $NOT$ included in $In-situ$ conservation?

$A$ charge $Q$ is enclosed by a Gaussian spherical surface of radius $R$. If the radius is doubled,then the outward electric flux will

$A$ body,thrown upwards with some velocity,reaches a maximum height of $50 \ m$. Another body with double the mass thrown up with double the initial velocity will reach a maximum height of $.......... \ m$.

If $x > 0$ and $x^y = e^{x-y}$,then $\frac{dy}{dx}$ is equal to

The value of $k$ for which the equation $x^2-4xy-y^2+6x+2y+k=0$ represents a pair of straight lines is equal to ........