Answer :
Answer:
[tex]P_2 O_5[/tex]has molar mass of 142 g.
Explanation:
Firstly we will find out the atomic weight of the elements of the compound.
Mg = 24 P = 31 Al = 27 Cl = 35 Ba = 137 O = 16
Now 1st compound is [tex]Mg Cl_2[/tex], in this compound there is 1 atom of Magnesium and 2 atom of Chlorine.
So atomic weight of [tex]Mg Cl_2[/tex]=[tex]24+2\times35=24+70=94[/tex]
2nd compound is [tex]P_2 O_5[/tex], in this compound there is 2 atom of Phosphorus and 5 atom of Oxygen.
So atomic weight of [tex]P_2 O_5[/tex] =[tex]2\times31+5\times16=62+80=142[/tex].
3rd compound is [tex]Ba Cl_2[/tex], in this compound there is 1 atom of Barium and 2 atom of Chlorine.
So atomic weight of [tex]Ba Cl_2[/tex]=[tex]137+2\times35=137+70=207[/tex]
4th compound is [tex]Al Cl_3[/tex], in this compound there is 1 atom of Aluminium and 3 atom of Chlorine.
So atomic weight of [tex]Al Cl_3[/tex]=[tex]27+3\times35=27+105=132[/tex]
Hence the substance having molar mass of 142 g is [tex]P_2 O_5[/tex].