<prompt> Which of the following statement about DDT is false-It is contact poisonResidual effect lasts for 18 monthsImmediately kills the preyPermethrin has synergistic action  <response>: Ans. is a i.e., Immediately kills the prey DDT Dichloro-diphenyl-trichloroetheine o DDT is an amorphous white powder. o Para-para isomer is the most active fraction -- contains 70-80 ofpara-para isomers. o It is primarily a contact poison. o It acts on CNS of insects and causes paralysis of legs and wings, convulsions and finally death. o It does not cause immediate death and takes several hours to kill the prey. o Its residual action may last as long as 18 months depending upon the treated surface. o It has no repellant action on insects. o Dose of DDT required is 100-200 mg per square foot. o Pyrethrum and DDT have synergistic action. 