Convex lens
Convex mirror
Concave lens
Concave mirror
Electrical conduction
Sonorous in nature
dullness
ductulity
Solid
Liquid
Gas
Vapour
Glycolic Acid
Lactic Acid
Citrus Acid
Tartaric Acid
the number of electrons in one atom
the number of neutrons in one atom
the valency of the element
the number of protons in one atom