The $DNA$ of $E. coli$ is . . . . . . .

If the direction cosines of two lines are given by $l+m+n=0$ and $l^2-5m^2+n^2=0$,then the angle between them is

Which of the following is the correct decreasing order of thermal stability of alkaline earth metal carbonates?

The equation of the straight line perpendicular to $5x - 2y = 7$ and passing through the point of intersection of the lines $2x + 3y = 1$ and $3x + 4y = 6$ is

An object,moving with a speed of $6.25\, m/s$,is decelerated at a rate given by $\frac{dv}{dt} = -2.5\sqrt{v}$,where $v$ is the instantaneous speed. The time taken by the object to come to rest would be ........ $s$.

Floral formula of Cruciferae (Brassicaceae) is$-$