What causes a nose bleed during the descent? I am not sure that the descent is correct here or not grammatically. If it is correct so what about descend, (the)descending?
Please add the reason of c... In both situations there is a lack of resources which causes people to die. This sentence should be read as follows: there's a lack of some resources, and it is this lack that's causing deaths. In effect, without those resources people die; the resources help avoid death.
causes of passing out for no reason, Unfortunately, there's a lack of those resources. This sentence makes sense, and is what you probably want to write. Or: Is this the only factor that causes such tragedies? In that form, the singular factor matches with the verb causes. Your sentence mixes the plural rooms with the singular factor, making it hard for you to figure out which form the verb cause (s) should take.
causes of passing out for no reason, (This isn’t necessarily ungrammatical, but sometimes this can make a sentence ... There is disagreement as to the causes of the fire. I remained uncertain as to the value of his suggestions. (2. meaning) according to, by. Example - The eggs are graded as to size and color.
As you have learned about the individual meanings of as to and as for, it's advisable to please go through the following usage notes.
