Which of the following is a secondary pollutant?

If $1$ is a multiple root of order $3$ for the equation $x^4-2x^3+2x-1=0$,then the other root is

The longest phase of meiosis is:

What is the decreasing order of reactivity amongst the following compounds towards aromatic electrophilic substitution?
$(i)$ Chlorobenzene
$(ii)$ Benzene
$(iii)$ Anilinium chloride
$(iv)$ Toluene

Which of the following shows the correct chronological order of the events occurring during callus culture?

Two ions of masses $4 \ amu$ and $16 \ amu$ have charges $+2 e$ and $+3 e$ respectively. These ions pass through a region of constant perpendicular magnetic field. If the kinetic energy of both ions is the same,then: