Ans 1.) Potassium ( 1 ) , palladium (2)
Metals are those which posses lustre, hardness, malleability, ductility etc.
Ans 2.) Oxygen ( 5 ) , Argon ( 4 )
Non metals are those elements which do not possess lustre, hardness, ductility, malleability etc... they are generally brittle in nature.
Ans 3.) Boron ( 3 )
Metalloids are those substances which shows both the properties of metals and nonmetals.
Ans 4.) Boron ( 3 )
Semiconductor are those substances whose conductivity is lie between insulators and conductors.
Ans 5.) Argon(4)
Least reactive gases are those gases which generally do not reactive with any element or having very least reactivity like argon which is noble gas.
Ans 6.) Oxygen (5)
Oxygen is dull, easily breakable and good insulator but only in solid form
Ans 7.) Palladium(2)
Malleability is the property of metals that is drawn metals into thin sheets .