The venous system of a frog differs from that of a rabbit in the presence of:

The eccentricity of the ellipse $9x^2 + 5y^2 - 30y = 0$ is

The reagent used for converting acetylene to oxalic acid is

The angle between the line joining the points $(1, -2)$ and $(3, 2)$ and the line $x + 2y - 7 = 0$ is

$A$ thief is running away on a straight road in a jeep moving with a speed of $9 \, m/s$. $A$ policeman chases him on a motorcycle moving at a speed of $10 \, m/s$. If the instantaneous separation between the jeep and the motorcycle is $100 \, m$,how long will it take for the police to catch the thief? (in $s$)

Plants are known as gymnosperms because -