It depends if it occurs naturally it has oxidation number of 0
but when it react with other element it has an oxidation number of -1
Answer:
It is true that earth was once covered with oceans and little dry land.
Explanation:
Over the course of around four billion years, the Earth's oceans have lost about a quarter of their original mass. Today the atmosphere is rich in oxygen, which reacts with both hydrogen and deuterium to recreate water, which falls back to the Earth's surface. So the vast bulk of the water on Earth is held in a closed system that prevents the planet from gradually drying out. According to the researchers, the continents emerged relatively suddenly from an ocean that covered 95 percent of the Earth's surface. The appearance of large masses of dry land would have caused more extreme weather, changes in ocean currents and the emergence of proper seasons. In turn, these environmental changes may have led to rise in atmospheric oxygen that enabled the explosion of new life forms around 500 million years ago.
Answer:
the physical and chemical properties of the products are different from the reactants
Explanation:
A chemical reaction involves the chemical combination of two or more elements/compounds called Reactants to give one or more different elements/compounds called Products. A chemical reaction occurs in such a way that the atoms of the reactants are restructured to form product(s) that is/are entirely different from the reactants.
In a chemical reaction, the physical and chemical properties of the products differ from that of the reactants since different chemical compounds/elements are formed as products. The physical properties of a substance, which include colour, melting and boiling point etc. will differ in the reactants and products formed. Also, the chemical structure and identity of the reactants will be changed to give rise to a different chemical property in the products.
C and D
surface water is evaporated by the sun and concentrated the ocean salt and oceans are diluted when rivers flow into them
Answer:
Detail is given below.
Explanation:
Similarities:
All are the forms of matter.
Solid, liquid and gases are made up of ions, atoms and molecules.
They have shape and volume.
Molecules in Liquid and solid are closer to each others.
Liquid and gases can flow very easily.
Liquid and solid both can not compressed very easily.
Differences:
Molecule of gases randomly move everywhere and occupy all available space but liquid and solid's molecules are not move as much easier as molecules of gases can.
The density of gases are very low as compared to the liquid and solid.
Gas molecules are at long distance from each other while in liquid and solid they are closer to each other.
The very weak inter molecular forces are present between gas molecules as compared to the liquid and solids.
Solids have definite volume and shape but liquid and gases acquire the shape of container.
In solids molecules are tightly pack and very close to each other while in liquid molecules are not tightly pack like in case of solid.
The densities of solids are also very high as compared to the liquid and gas.
There are very strong inter molecular forces are present between solid molecules.
