In which of the following is the $P - O - P$ bond present?

Electric field at a point varies as $r^0$ for

If the altitudes of a triangle are in arithmetic progression,then the sides of the triangle are in

If $x$ is the specific conductance (in $S \ cm^{-1}$) of the electrolyte solution and $y$ is the molarity of the solution,then $\Lambda_m$ (in $S \ cm^2 \ mol^{-1}$) is given by:

The operation of a nuclear reactor is said to be critical when the value of the neutron multiplication factor $K$ is:

Which one of the following is a correct set?