Wind pollination is common in . . . . . . .

The time taken by a photoelectron to come out after the photon strikes is approximately

$A$ uniform metal rod is used as a bar pendulum. If the room temperature rises by $10^{\circ} C$ and the coefficient of linear expansion of the metal of the rod is $2 \times 10^{-6} /^{\circ} C$,the period of the pendulum will have a percentage increase of

The discovery of the fungicide known as Bordeaux mixture is associated with which of the following diseases?

The pair of compounds which cannot exist together in aqueous solution is
$I$. $NaH_2PO_4$ and $NaHCO_3$
$II$. $Na_2CO_3$ and $NaHCO_3$
$III$. $NaOH$ and $NaH_2PO_2$
$IV$. $NaHCO_3$ and $NaOH$

If the centroid of the triangle formed by the lines $2y^2 + 5xy - 3x^2 = 0$ and $x + y = k$ is $\left(\frac{1}{18}, \frac{11}{18}\right)$,then the value of $k$ equals $............$