● The crust is an outer thin layer with a total thickness normally between 30-50 km. Hence statement 3 is not correct. ● The continents are composed of lighter silicate such as silica and alumina. ◦ It is also called 'SIAL'. ◦ They are made up of Granitic rocks. Hence statement 1 is not correct. ● Oceans are having higher silicates such as silica and magnesium. ◦ It is also called 'SIMA'. ◦ They are made up of Basaltic rocks. Hence statement 2 is not correct.