It depends on your doctors advice. Usually three months before trying to conceive again. If you had a molar pregnancy you should be having regular checkups to ensure that all the prregnancy hormone has gone. As Trisha said you should wait until the doctor tells you it is all right to conceive again. According to the website http://health.allrefer.com/health/hydatidiform-mole.html this may be 6 to 12 months. it is mis-spelled above, try "molar pregnancy" if you Google that, you will easily find your answer.
I had a molar pregnancy and my doctor recommended to wait at least one year to try again. Then I had a miscarriage and after that, I had two more kids.
Yes it can!
risk of uterine perforation
It is possible that you may have a molar pregnancy. You should see your doctor for more information.
molar , twin as well as ectopic pregnancy
A molar pregnancy occurs when instead of a baby forming inside of your uterus, basically a cluster of just tissue forms due to a genetic error. A partial molar pregnancy occurs when part of the cell is a healthy embryo and part of it contains abnormal cells. This can also occur (but is rare) with twins when one is a healthy embryo and other is a mole. Usually the mole ends up overtaking the healthy embryo.
I don't think an ectopic pregnancy can be treated, the same goes with a molar pregnancy, im sure they would both have to be removed. Go see your doctor. Hope this helps.
the PH will be the same
There are two facts you should obtain to calculate the molar mass of a hydrated compound. Those are the molar mass, say 'M' and the number of hydration 'N'. Then the molar mass of the compound can be obtained by M + 18N. (The molar mass of a water molecule is 18 g/mol)
Sand is mostly silicon dioxide, SiO2. It should be trivial to calculate the molar mass of that (I'm not going to do it for you, though).