Chemistry Questions

Atomic number is the serial number of an element in the periodic classification of elements. It gives the number of protons and also the number of electrons in an atom.

While moving from left to right in periodic table basic character of oxide of elements will decrease.

  ∴→Increasing basic strengthAl2O3<MgO<Na2O 

and while descending in the group basic character of corresponding oxides increases. 

 ∴→Increasing basic strengthNa2O<K2O

∴ Correct Order is Al2O3 < MgO <Na2O <K2O

A pure substance can be defined as any single type of material that has not been contaminated by another substance. In chemistry, a pure substance has a definite composition. It can be a compound or an element. A pure substance is considered to be a material that consists of one type of "building block" of matter.

Examples of pure substances include tin, sulfur, diamond, water, pure sugar (sucrose), table salt (sodium chloride) and baking soda (sodium bicarbonate).

Tin, sulfur, and diamond are examples of pure substances which are chemical elements. All elements are pure substances.

Water, sugar, salt and baking soda are pure substances which are chemical compounds. Chemical compounds also are pure substances