Substituents on an aromatic ring can have several effects on electrophilic aromatic substitution reactions. Substituents can activate or deactivate the ring to substitution, donate or withdraw electrons inductively, donate or withdraw electrons through resonance, and direct substitution either to the ortho/para or to the meta positions. From the following lists, select the substituents that have the indicated property. The substituents are written as -XY, where X is the atom directly bound to the aromatic ring.

Activation of the ring towards substitution

-NHCOCH3

-CH3

Withdrawal of electrons through resonance

-NO2

-CN

Ortho/para-directed substitution

-CH3

-OH

Explanation:

The substituents present on an aromatic ring strongly influence in its reactivity.

An activating group is one whose presence increases the reactivity of the aromatic ring against the aromatic electrophilic substitution with respect to when that group is absent. The introduction of an activating group in an unsubstituted aromatic compound will frequently lead to a polysubstitution.

This increase in reaction rate is due to the fact that these groups stabilize the cationic intermediate formed during the substitution through the transfer of electronic density on the annular system, either by inductive effect or by resonant effect.

A deactivating group is one whose presence decreases the reactivity, the reaction rate, of the aromatic ring against the aromatic electrophilic substitution with respect to when that group is absent. Therefore, the introduction of a deactivating group in an unsubstituted aromatic compound will make a second substitution more difficult.

In a benzene substituted with an electron donor group, either by inductive or resonant effect, an electrophilic substitution reaction will mainly result in a mixture of ortho and para products, the minority target product being.

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.

the correct answer is b. a strong acid completely dissociates to its ions when dissolved in water. completely dissociates to and ions. a is incorrect because does not fully ionize to and ions and some remain as the compound . c and d are incorrect because, and do not fall into the category of bronsted lowry acids. a bronsted lowry acid is a proton donor and since both molecules do not have a proton to donate they are not bronsted lowry acids. likewise,   if we use the lewis acid definition, they cannot be acids. a lewis acid is an electron pair acceptor. both and have a complete octet so can not accept any electrons which disqualifies them as acids.