Question

why is the seawater is salty

Answer 1

Salt in the ocean comes from rocks on land. The rain that falls on the land contains some dissolved carbon dioxide from the surrounding air. This causes the rainwater to be slightly acidic due to carbonic acid (which forms from carbon dioxide and water). ... Sodium and Chloride are 'salty.'

Answer 2

we know that soil contain many mineral and salt.when the river passes through sand , it dissolve that salt in it . ultimately when river emerges with sea,the salty water get deposited in it

note that the salt is not in the high amount in soil so river water doesn't taste salty but most of river deposit this salty water in sea creating the collection of large salty water bodies.that is why sea water is salty