Depends on what you mean by strong, both of these drugs come in a wide variety of quality that vary greatly in strength. Both drugs also interact with the mind and body in different ways, making it hard to say which one is "stronger".
you cant.
No, Heroin is derived from opium coming form the poppy. Cocaine comes from the coca leaf.
no.
Either heroin, or cocaine.
100
Yes, Heroin - 5 times to death Morphine - 10 times to death
Let me start by stating that I assume you meant "heroin". Anyway, no, the chemical structures of these compounds are completely different. Heroin is derived from morphine whereas cocaine is a tropane alkaloid. Thus, it is not possible to convert cocaine to heroin.
Speeball
Both cocaine and heroin will effect your concentration. You do not want to take these substances and then get behind a wheel.
Doing an upper like cocaine and a downer like heroin at the same time is called speed balling. A different sort of high than either individually used.
no just cocaine will
No. Not at all.