Yap example sentences

Soluble fluoride is often added to drinking water to bring its concentration upto 1 ppm or 1 mg dm– The F– ions make the enamel on teeth much harder by converting hydroxyapatite, [3(Ca3(PO4) Ca(OH)2], the enamel on the surface of the teeth, into much harder fluorapatite.The Chera kingdom of Mahodayapuram was established in the ninth century in the south-western part of the peninsula, part of present-day Kerala.