Explanation;
Bromine test is done to distinguish between the unsaturated hydrocarbons from saturated hydrocarbons.
When we add bromine water to an unsaturated hydrocarbon ,bromine atoms get attached to the carbons with double bond in between. This reaction between bromine water and unsaturated hydrocarbon results in de-colorization of bromine water color from red to colorless.
When bromine water is added to hexane no color change will be observed.
no reaction
When bromine water is added to 2-hexene color change will be observed.

A toxic substance<span> is a </span>substance<span> that can be poisonous or cause health effects. People are generally concerned about chemicals like polychlorinated biphenyls (PCBs) and dioxin which can be found at some hazardous waste sites.</span>
The question is incomplete. To complete it you must include the moles of N2 and then you can use the ideal gas law to solve for the mass.