Elimination reaction (especially `beta` - elimination) are as common as the nucleophilic substitution reaction in case of alkyl halides. Specify the reagents used in both cases.

Explanation

Elimination reactions are as common as the nucleophilic substitution reaction in case of alkyl halides as two reactions oCcur simultaneously. Generally, at lower temperature and by using weaker base nucleophilic substitution reaction occur while at higher temperature and by using a stronger base elimination reactions (especially `beta`-elimination) take place. e.g., If ethyl bromide is treated with aq. KOH, at low temperature it gives ethanol while if it is treated with alc, KOH at high temperature then it gives ethene.
`CH_(3)CH_(2)Brunderset(373 K)overset(Aq. KOH)tounderset("Ethanol")(CH_(3)CH_(2)OH)`(Nucleophilic substitution reaction)
`CH_(3)CH_(2)Brunderset(473-523K)overset(Alc KOH)tounderset("Ethene")(CH_(2)=CH_(2))`(Elimination reaction)