Question

In general, the ld50 for exotoxins is much greater than the ld50 for endotoxins.

Answer 1

FALSE!!
Endotoxins are just the lipid parts of a gram negative cell wall that have broken off when the bacteria dies. They are moderately toxic, cause fever and can make you pretty sick.
Exotoxins are proteins made by pathogenic bacteria (mostly gram positive). These highly toxic. Examples of diseases caused by these are diphtheria, botulism and tetanus. 
Therefore it doesn't take much exotoxin to cause a problem!