A pure substance/element contains
A pure substance has a constant composition and cannot be separated into simpler substances by physical means. Elements: are pure substances made up of only 1 type of atom. Atoms of the same element are identical in properties.
The smell of hydrogen sulphide (H2S) gas
Hydrogen sulfide is a flammable, colorless gas with a characteristic odor of rotten eggs. It is commonly known as hydrosulfuric acid, sewer gas, and stink damp. People can smell it at low levels.
Which of the following is not a mixture?
Carbon dioxide is not a mixture since it contain fixed ratio of oxygen and carbon in 2:1, which is a property of compound not a mixture.
Which of the following is a true solution?
Salt solution is a true solution.
Which of the following is a chemical change?
Cooking of food is a chemical change because after cooking, the raw ingredients or the vegetables cannot be regained again in the raw form.
The process of separation of insoluble solids from a liquid is called:
Filtration is a method for separating an insoluble solid from a liquid. When a mixture of sand and water is filtered: the sand stays behind in the filter paper (it becomes the residue ) the water passes through the filter paper (it becomes the filtrate )
Which of the following has the highest solubility at 313 K?
An example of a liquid metal and a liquid non-metal is
Mercury is the only liquid metal and bromine is the only liquid non-metal.
-Mercury is the only metal that is a liquid at normal temperatures and pressure.
-Because of the behavior of the valence electrons, mercury has a low melting point, is an electrical and thermal conductor and doesn't form diatomic mercury molecules in the gas phase
Bromine has 35 electrons and with7 electrons in its outer shell it has a valency of 1 so, is very reactive.
But, the electrons are very spread out from the atomic nucleus, hence it behaves like a liquid.
- It is non-metallic because it is a halogen gas that is liquid at STP.
Alloys are homogeneous mixtures of two or more elements. The elements could be two metals, or a metal and a non-metal.
Brass is an example of a
Brass is an alloy made up of uniform composition of copper and zinc. It is a homogeneous mixture in which zinc and copper can be varied to create a range of brasses with varying properties.