Sins And Hell

[Chanman450]

If someone would commit a mortal sin for which they are not sorry for, and then die while still unrepentant for that mortal sin, would that person be guaranteed (spelling) to go to hell?

What is the unforgiveable sin? If someone would die while guilty of this sin, would that person be guaranteed to go to hell?

It is a mortal sin to have premarital sex even if it is only done for a short time and ejaculation does not occur right?

[cappie]

From the Catechism of the Catholic Church

1035 The teaching of the Church affirms the existence of hell and its eternity. Immediately after death the souls of those who die in a state of mortal sin descend into hell, where they suffer the punishments of hell, "eternal fire." The chief punishment of hell is eternal separation from God, in whom alone man can possess the life and happiness for which he was created and for which he longs.

The unforgivable sin I think is to refuse to accept forgiveness from God to refuse to repent and thus God cannot forgive e.g. the choice of the bad angels

393 It is the irrevocable character of their choice, and not a defect in the infinite divine mercy, that makes the angels' sin unforgivable. "There is no repentance for the angels after their fall, just as there is no repentance for men after death."

Premarital sex entered into knowingly and freely is a mortal sin

1857 For a sin to be mortal, three conditions must together be met: "Mortal sin is sin whose object is grave matter and which is also committed with full knowledge and deliberate consent."