Who is to pay the zakat on the 5,0 euros that the questioner gave to his brother, which the brother then deposited into his bank account, bearing in mind that the time for its zakat payment is due in August? And what is the ruling on informing family members when lending money to someone, as a precautionary measure in case of death?

The land became your property after you paid its price, so there is no zakat due on what you paid. As for the seller, he owes zakat on the amount if a full lunar year has passed over it, provided it remains in his possession. Regarding the remaining ten (units of currency) that are your liability, there is a jurisprudential dispute about deducting them from zakat funds, and we have clarified the most authoritative opinion in Fatwa no. 100534. Your lending to the person and informing your family about it is a good deed for which you will be rewarded.