The answer is : Ka=0.000137
HA -> H+ + A-
0.10 x x
0.10-x +x +x
[H+]= 10^-2.44 = 0.00363
x= 0.00363
(0.00363)(0.00363)/(0.10-0.00363) = 0.000137
Ka=0.000137
Before cellphones are able to be used to browse the internet, play games, record videos and take photos, its main purpose is similar to a telephone, albeit it is more portable. Early cellphones would not have games for you to play, not would it have emails for you to check, read, and reply to. Though ringtones might seem as an acceptable option, early cellphones would also have many selections or even any for you to choose.
Thus, the best option would be (B) contact list, which is necessary for a cellphone to have since the owner would need the number to be able to make a call.
