What is the percentage composition for H2O in this compound Al(OH)3.2H2O? a
50.55%
b
40.05%
c
32.73 %
d
65.09%

32.73%

Explanation:

To solve this problem, first find the molar mass of Al(OH)₃.2H₂O

 Atomic mass of Al  = 27g/mol

                            O = 16g/mol

                            H  = 1g/mol

Molar mass = 27 + 3(16 + 1) + 2(2(1) + 16)

                    = 27 + 51 + 36

                   = 114g/mol

Percentage composition  = x 100 = 32.73%

you need to take a look at the periodic system in order to sort these elements into pairs that would most likely exhibit similar chemical properties. first, you need to find elements that are found in the same group (groups are vertical in the periodic system), and then to see whether they have the same valence number. if they meet these criteria, they will have similar properties.

the first pair: ne (neon) and kr (krypton), are noble gases found in group 8

the second pair: li (lithium) and k (potassium), found in group 1

the third pair: s (sulfur) and te (tellurium), found in group 6

the correct option is c.

isotopes refers to different forms of the same element with the same atomic number but different mass number as a result of difference in their neutron numbers. isotopes have different relative atomic mass but share the same chemical properties.