Which of this is the method by which fire extinguisher works?
a) the cut of oxygen supply to the burning substance.
b) the reflect away the heat because of there colour and does cool down the burning substance.
c)the exert force on the substances, that has caught on fire because of which the fire gets extinguish.
d)they release chemicals, which react with oxygen in the air and stop it form reaching the burning substances.

the answer is a.cut off the supply of oxygen

Option D

Explanation:

There are 5 main fire extinguisher types – Water, Foam, Dry Powder, CO2 and Wet Chemical. Hence the different chemicals released will react with oxygen in the air to prevent the fire from getting sufficient oxygen and spreading.

answer: the enthalpy of the overall chemical reaction is +87.88 kj or +88 kj.

according to hess's law, the overall enthalpy of a reaction is the difference between the sum of enthalpy values of all the products and the sum of enthalpy values of all the reactants.

δh(reaction) = ∑nδh(products) - ∑nδh(reactants)

δh(reaction) = [δh +δh] - [δh]

δh(reaction) = [1(-287.02) + 1(0) ] - [1(-374.9)] kj = +87.88 kj

here, δh (pcl3) = -287.02 kj, δh(cl2) = 0, δh(pcl5) = -374.9 kj

therefore, enthalpy of the overall reaction is +87.88 kj or +88 kj.