(i) Sodium imparts a golden yellow colour to the flame.
(ii) Because of its smallest size among alkali metals. Li+ has the maximum degree of hydration. That’s why lithium salts are commonly hydrated and those of other alkali metal ions usually anhydrous.
(iii) KOH is a stronger base than NaOH. Due to large size of K, K—O bond is weaker than Na—O bond. KOH has more concentration of OH than NaOH, hence, is a stronger base than NaOH.