Question

The number of metalloids in the modern periodic tables are :
A. 4
B. 5
C. 6
D. 7

Answer 1

In the modern periodic table the metalloids are separated from the metals and non - metal with a zig - zag line . They show the properties of both metals and nonmetals .

Complete step by step answer: Metalloids are elements which show the properties of both metals and non - metals therefore in the periodic table also they are seperated from metals and non - metals by a zig-zag line .
In the modern periodic table there are six metalloids which are boron , silicon , germanium , arsenic , antimony and tellurium .
Metalloids usually look like metals but they behave largely like non metals.
Physically, they are shiny, brittle solids with intermediate to relatively good electrical conductivity and the electronic band structure of a semimetal or semiconductor.
Chemically, they mostly behave as weak nonmetals,they have intermediate ionization energies and electronegativity values, and amphoteric or weakly acidic oxides. Most of their other physical and chemical properties are intermediate in nature.
Metalloids don't have any structural use in their pure form as they are too brittle .Therefore they and their compounds are used to form alloys , biological agents ( toxicological , nutritional , and medicinal ) , catalysts , flame retardants , glasses (oxide and metallic) , optical storage media and optoelectronics , pyrotechnics , semiconductors , and electronics .
Option C is correct.

Note: Metalloids are sometimes called semimetals but it is not encouraged as the term semimetal has a different meaning in physics than in chemistry .
There are five elements which are less commonly recognised as metalloids : carbon, aluminium, selenium, polonium, and astatine .