(a)How many moles are present in 11.5g of sodium?
(b)The mass of an atom of element (X) is `2.0xx10^(-23)g`. Calculate its atomic mass.

Explanation

Gram atomic mass of Na=23g
23g of Na represent =1 mol
11.5g of Na represent=`((1"mol")xx(11.5g))/((23.0g))=0.5"mol"`
(b) One atom of element (X) has mass=`2.0xx10^(-23)g`
`=12.044gcong12.0g`