Carbon dioxide is used in fire extinguishers because it is heavier than air.

Gold is not used for electrical wiring because of its high cost.

Hydrogen is a non-metal (and usually a gas). It appears on the left side of the periodic table only because it has a +1 charge, as do the other elements in that column (Group 1).

Biogas usually contains about 55 - 65% methane.

Base + Metal  = Salt + Hydrogen Gas

Magnesium is found in plants in the form of chlorophyll.

Phosphorus ion P^- is highly reactive.

Magnesium oxide dissolves in water and its solution is basic in nature.

Copper sulphate is blue in colour because it has been oxidised to the Cu2+ ion which is a d-block metal ion.

When blue litmus paper is immersed in an acid, the litmus paper turns red.

Sulphur dioxide dissolves easily in water to form sulphuric acid. Sulphuric acid is a major component of acid rain.

Bromine, a non-metallic chemical element with a valence of one, is only halogen which is liquid at room temperature.

Mg metal plus oxygen makes MgO called magnesium oxide.

The most abundant metal is aluminium. It weighs 8.23 percent of the earth's crust.

Silver cannot react with hydrochloric acid.