The correct answer is 'X' is a base and is an alkali.Concept:pH scale:A scale developed to measure the concentration of hydrogen ions in a solution is known as the pH scale where p in pH implies potenz in German.pH scale ranges from 0 (highly acidic) to 14 (highly alkaline).The pH of a neutral solution is 7.An acidic solution is represented by a value less than 7 on the pH scale whereas the basic solution is represented by a value greater than 7 on the pH scale.Explanation:Bases:They are bitter in taste. They are slippery and soapy to touch.They turn red litmus blue. Bases soluble in water are called Alkalis. They have a pH greater than 7. Thus, X is a base as well as an alkali.Additional InformationAcids:They are sour in taste. They turn blue litmus red.They have a pH lower than 7.