Base your answers to questions 54 and 56 on the information below and on
your knowledge of chemistry.
Three elements, represented by D, E, and , are located in Period . Some
properties of these elements are listed in the table below. A students
experimental result indicates that the density of element is 2.10g/cm3
at room temperature and standard pressure.
54 Identify the physical property in the table that could be used to
differentiate the samples of the three elements from each other. 
55 Identify the group on the Periodic Table to which element D belongs.
|Answer--> Group 1 (also acceptable alkali
56 Determine the percent error between the students experimental density
and the accepted density of element . 
work not required
%error =((2.10-2.00)/2.00) x 100%