Why sea water boils at higher temperature than distilled water ?

In a dam , the surface water is at higher temperature than the water deep within the dam .

Sodium chloride solution freezes at lower temperature then water but boils at higher temperature than water. Explain.

Why does water boil at a lower temperature in Nainital than in Delhi.

Assertion: Water boils at higher temperature in pressure cooker. Reason: Increase in pressure leads to an increase in boiling temperature.

Water boils at lower temperature on high altitude because:

Water boils at a lower temperature than 100^@C on a hill station because

Water boils at a lower temperature than 100^(@)C on a hill station because