Asubstance is tested with litmus paper. the blue litmus paper remains blue while the red litmus paper remains red. what can you conclude about the substance?

the substance is a base.
the substance is neutral; it is neither an acid nor a base.
the substance could be either an acid or a base.
none of the above; it is impossible for both red and blue litmus paper to remain unchanged.

Option (b) is the correct answer.

Explanation:

A substance that is acidic in nature will have pH less than 7 and it will turn blue litmus into red.

Whereas a substance that is basic in nature will have pH more than 7 and it will turn red litmus into blue.

And, a substance that has pH equal to 7 will be neutral in nature and it will not change the color of blue or red litmus paper.

Thus, we can conclude that when a substance is tested with litmus paper. The blue litmus paper remains blue while the red litmus paper remains red. Then it means that the substance is neutral; it is neither an acid nor a base.

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.