Spraying of $D.D.T.$ on crops produces pollution of

Which kingdom includes unicellular protozoans and primary aquatic eukaryotic organisms?

$A$ train leaves Pune at $7:30\,am$ and reaches Mumbai at $11:30\,am$. Another train leaves Mumbai at $9:30\,am$ and reaches Pune at $1:00\,pm$. Assuming that the two trains travel at constant speeds,at what time do the two trains cross each other?

Which of the following acts as a rocket propellant?

The contrapositive of the statement "If two numbers are not equal,then their squares are not equal" is

If the angle between the pair of lines $x^2+2 \sqrt{2} x y+k y^2=0, k>0$ is $45^{\circ}$,then the area (in square units) of the triangle formed by the pair of bisectors of the angles between these lines and the line $x+2 y+1=0$ is