Triphenylmethane can be prepared by reaction of benzene and chloroform in the presence of AlCl3. Draw curved arrows to show the movement of electrons in this step of the reaction mechanism.

a gas, having a molecular weight of 13 kg/kmol and a kinematic viscosity of 0.25 cm2/s, flows through a pipe 0.25 m internal diameter and 5 km long at the rate of 0.4 m3/s and is delivered at atmospheric pressure.

it's c (engineer's do their work with mechanical stuff not on any living being)