A pure substance/element contains:
The smell of hydrogen sulphide (H2S) gas:
Hydrogen sulfide is a flammable, colorless gas with a characteristic odour 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?
True Solution is a homogeneous mixture of two or more substances in which substance dissolved (solute) in solvent has the particle size of less than 10-9 nm or 1 nm. Simple solution of salt in water is an example of true solution. Particles of true solution cannot be filtered through filter paper and are not visible to naked eye.
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?
∴ KNO3 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.
Alloys are homogeneous mixtures of two or more elements. The elements could be two metals, or a metal and a non-metal.
Example: Brass is an example of a substitution alloy of copper and zinc.
Brass is an example of:
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.