Explanation:

here are many chemicals in seawater that make it salty. Most of them get there from rivers carrying chemicals dissolved out of rock and soil. The main one is sodium chloride, often just called salt. Most seawater has about 35g (7 teaspoons) of salt in every 1000g (about a litre) of water. This doesn’t sound very much, but it would take three 6m shipping containers full of salt to make an Olympic-size swimming pool as salty as the sea.The commonest way to record salinity is to measure the amount of salt in 1000g of water, so it is referred to as ‘parts per thousand’ or ppt. Most of the ocean has a salinity of between 34ppt and 36ppt.