Consider the following statements regarding bases and alkalis: 1. All bases dissolve in water. 2. Bases which are soluble in water are called alkalis. 3. An alkali is soapy to touch, bitter and corrosive. 4. Addition of water to an alkali generates heat. Which of the statements given above are correct?

Statement 1 is incorrect: NOT all bases dissolve in water — many metal oxides/hydroxides like Cu(OH)2, Fe(OH)3, Al(OH)3 are insoluble bases. Statement 2 is correct: alkalis are by definition water-soluble bases (e.g., NaOH, KOH). Statement 3 is correct: alkalis feel soapy/slippery, taste bitter, and are corrosive to skin. Statement 4 is correct: dissolving alkalis like NaOH in water is highly exothermic and releases heat. Hence statements 2, 3 and 4 only are correct.