Boys sperm is called semen. :)
Yes but some time will have to pass before you can do it again
There's no way the girl will get pregnant, because the boy did not ejaculate, so that means no sperm or semen excreted that will fertilize a mature egg of the female.
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no not as long as no semen has entered her
no
There is no difference between sperm/semen of white boy and black boy just as there is no difference in their blood.
No, it does not hurt. There is a strange sensation which is enjoyable. The more often the boy masturbates the more enjoyable the ejaculation of semen becomes.
by eating carrots.
As long as they don't have an STD, nothing happens.
That is a personal question for specific girls. Some do, some don't.
At 13-years-old a boy may not yet be producing any semen. Puberty ranges are different for every boy so it is not possible to be precise for individuals. It can be anywhere from nothing to full adult production !