As per IS-456, where freezing and thawing actions under wet conditions exit, inhance durability can be obtained by the use of suitable air entraining admixture. The entrained air percentage can vary from 4±1 to 5±1 (i.e. 3 to 6%) depending on size of aggregate. Hence, Assertion (1) is correct. Equivalent alkali content (in terms of Na2O equivalent) =Na2O+0.658×K2O Molecular ratio of Na2O to K2O=0.658 =1%+0.658×0.6%=1.39 ≃1.4 (rounded to 1 decimal place).