See explanation
Explanation:
Sea water = a mixture of different substances in water. If the water evaporates, some of those substances remain as salts. It's not a compound because it's a mixture of compounds and substances. An example of a compound is water ( because it has hydrogen atoms and an oxygen atom)
Calcium = Calcium is found on the periodic table so it cannot be a compound or mixture. It's a metallic element because we can find it on the left side of the periodic table, in group 2. Â It's an alkaline earth metal, what makes that calcium is a reactive metal.
Argon = Argon is found on the periodic table, so it can't be a mixture or compound. It is a non-metallic element. We can find it in group 18 on the periodic table. Argon is a noble gas, so non-metallic.
Water = a compound because its only made of 2 atoms : oxygen and hydrogen. Â Reasons why water is a compound and not a mixture are:
 - The ormation of a compound is a chemical change which is followed by absorption of energy or evolution of energy, in case of water, electricity is required.
- Mixtures can be separated by physical separation techniques ,Water can not be separated into it its elements by physical separation techniques. But by the absorption of chemical energy.
Air = Mixture because it can be separated into different atoms, molecules,.. Â like oxygen, nitrogen etc. by the physical separation techniques (fractional distillation).
Carbon Monoxide = Carbon Monoxide is not found on the periodic table so it cannot be an element. It's made of 2 elements, this means caron monoxide is a compound. It's not a mixture since the elements cannot be separated by physical separating techniques.
Iron = Iron is found on the periodic table so it cannot be a compound or mixture. It's a metallic element because:
-High melting point
- Â Some metals form a dull oxide layer, this explains the shiny luster surface
- Electrical conductivity and thermal conductivity
Sodium chloride = NaCl cannot be found on the periodic table, so it isn't an element. It's a compound because it only has 2 atoms (elements). Those elements cannot be seperated by physical separating techniques, but would require electricity. So it's a compound.
Diamond = is a solid form of the element Carbon. Â It's an allotrope of carbon. They have the same physical state but in distinct form. Technically diamond is a non-metallic element. Since it's seen as carbon.
Brass = Brass is a mixture of the elements of copper and zinc. Those elements can be separated by physical techniques.
Copper = Copper is found on the periodic table so it cannot be a compound or mixture. It's a metallic element because:
-High melting point
- Â Some metals form a dull oxide layer, this explains the shiny luster surface
- Electrical conductivity and thermal conductivity
Dilute sulphuric acid = This is a mixture. Sulphuric acid is a compound but to dilute it's added in water, what is another compound. So it's a mixture of different compounds.
Sulphur = Can be found in the periodic table so it cannot be a mixture or compound. It's part of the metalloids, therefore, it can be concluded that sulfur is a non-metal. It belongs to the oxygen family.
Oil = Oil is a mixture of hydrocarbon compounds which varies in lengths.
Nitrogen = Nitrogen is found on the periodic table, so it can't be a mixture or compound. It can be found as a gas so it is a non-metallic element.
Ammonia = a compound of nitrogen and hydrogen with the formula NH3. Those elements cannot be separated with physical separating techniques.
