What is the undifferentiated mass of cells in tissue culture called?

Excess of which of the following in water causes blue baby syndrome disease?

The least number among $\sqrt[3]{4}, \sqrt[4]{5}, \sqrt[4]{7}$ and $\sqrt[3]{8}$ is:

Which of the following is a part of the pistil (gynoecium)?

Charges of $2 \mu C$ and $-3 \mu C$ are placed at two points $A$ and $B$ separated by $1 \ m$. The distance of the point from $A$,where the net potential is zero,is (in $m$)

The property of hydrogen which distinguishes it from alkali metals is