▪️Most abundant element on earth’s crust – Oxygen

▪️Most abundant metal in earth’s crust – Aluminium

▪️Most abundant metalloid in earth’s crust – Silicon

▪️Most abundant element in atmosphere – Nitrogen

▪️Most abundant element in the universe – Hydrogen

▪️Most abundant element in human body – Oxygen

▪️Most abundant gas in atmosphere – Nitrogen

▪️Most abundant element in sea water – Chlorine

▪️Most abundant element in moon’s surface – Titanium

▪️Most abundant metal present in human body and bones – Calcium

▪️Most abundant metal compound in bones – Calcium phosphate

▪️Most abundant compound on earth’s surface – Water (H2O)

▪️Most abundant compound in sea water – Sodium Chloride

▪️Second most abundant compound in sea water – Magnesium Chloride

▪️Most chemically reactive element – Fluorine

▪️Second most chemically reactive element – Chlorine

▪️The lightest and simplest element – Hydrogen

▪️The lightest metal – Lithium

▪️The rarest element in the earth – Astatine

▪️The heaviest element – Osmium

▪️The heaviest gaseous element – Radon

▪️First man made element – Technetium

▪️Most stable element – Lead

▪️The periodic table is divided into 4 main blocks
▪️S block – elements of group 1 and 2
▪️P block – elements of group 13 to 18
▪️D block – elements of group 3 to 12
▪️F block – Lanthanides and Actinides

▪️The shortest period of the periodic table
Ans : First period

▪️The longest period of the periodic table
Ans : Sixth period

▪️Elements with atomic number 57-71 are known as
Ans : Lanthanides (rare earths)

▪️Elements with atomic number 89-103 are known as
Ans : Actinides (radio active rare earths)

▪️Total number of elements in periodic table
Ans : 118

▪️The number of naturally occurring elements
Ans : 92

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