What are the physical and chemical properties of Water? (H20)

                                                      These are the properties of a substance which can be observed without changing the physical appearance of a substance.

          Example :

                            (i) Boiling Point: Water has a boiling point of 100 °C at sea level. At this temperature the water changes its state from liquid to vapors (gas).

                            (ii) Melting Point: Water has a melting point of 0 °C. At this temperature the water changes its state from solid to liquid.

                            (iii) Freezing Point: Water has a melting point of 0 °C. At this temperature the water changes its state from liquid to solid.

                            (iv) Density: The density of water is about 1 g/ml at 20 °C.

                            (iii) Heat Capacity: Heat capacity of water is 4.186 joule/gram °C.

                                                      These are the properties of a substance which can be observed only by changing the identity of a substance.

          Example :

                            (i) Stable Compound: Water is said to be a very stable compound. It means it cannot decompose easily. Hence, has a stable bonds. This stability can be termed as chemical property.

                            (ii) Reactions with Metals: With reaction with metals the water produces hydrogen gas and corresponding metal hydroxide.

                            (iii) Reactions with Metal Oxides: Upon reaction with metal oxides water produces bases.

                            (iv) Reactions with Non-Metals: Upon reaction with non-metals water produces corresponding acids.

the answer is 1 i believe

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.