When Allah told the Angels that He will place a viceroy on Earth, referring to the Creation of Adam (Alaihi As-Salaam) [Ref Surah Baqarah Verse: 29], the Malaaikah asked Allah if it will be one who will shed "Blood" and perform mischievous acts. How can the Angels know this if they knew not of Adam (Alaihi As-Salaam), i.e. how can they know if that a person can do wrong if they only know to worship and can't do wrong, referring to shedding blood? Angels are made not blood, how can they know this?

Praise be to Allah, the Lord of the World; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

Commentators of the Qur'an mentioned several interpretations of Allah's statement: {And (remember) when your Lord said to the angels: "Verily, I am going to place (mankind) generations after generations on earth." They said: "Will You place therein those who will make mischief therein and shed blood, - while we glorify You with praises and thanks (Exalted be You above all that they associate with You as partners) and sanctify You." He (Allâh) said: "I know that which you do not know."} [2: 30].
First, Angels said the above-stated in the verse after He, The Exalted, has informed them of the nature of the offspring of Adam () whose nature is to shed blood and to make mischief on earth. This is narrated from Ibn Abbas , Ibn Masoud , Ibn Juraij , Ibn Zaid and others as recorded by al-Qurtubi and Ibn Kathir . It is reported that Allah said to the Angels: "I will Create a vicegerent on earth". The Angels said: 'What are the qualities and nature of that vicegerent?' Allah said: "His offspring will make mischief on earth, envy one another and kill one another" .
Qatada added: 'Allah, The Exalted, has informed the Angels that the coming creatures on earth will make mischief and shed blood. For such a reason they said: 'Will you place on earth those who will make mischief on earth?' .
Second, when the Angels heard the word Khalifa (vicegerent), they deduced that some of the offspring of Adam will make mischief, since the Khalifa is meant for reform and giving-up corruption, establishing justice among people and deterring them from doing prohibitions.
Third, al-Qurtubi (may Allah's Mercy be upon him) and other scholars reported that the Angels witnessed and knew the mischief and bloodshed done by the Jinn, who were living on earth before the creation of Adam . Thus, He Sent the Devil, before becoming a disbeliever, and his followers against the Jinn, who resorted islands and edges of mountains. Then, He Created Adam and placed him on earth. This narration is from Ibn Abbas and Abu al-Aliyah .
Then, it should be known that such a saying of the Angels, i.e. about the creation of Adam and his being a Khalifa on earth, does not constitute an objection to Allah's Will. It, according to Ibn Kathir (May Allah's Mercy be upon him) is a form of inquiry that aims at recognizing wisdom behind the act of Divine Order. In other words, the Angels say: 'What is the wisdom of creating such beings, although they make mischief and shed blood on earth?' Then, if the goal is to worship You, then we (Angels) glorify You with praises and thanks and sanctify You, i.e. pray to You and Obey You, why isn't Your choice limited to us?
Allah, The Exalted, has replied them with: {"I know that which you do not know."} .
This verse indicates that Allah knows what His Creatures do not know, even the evil they mentioned (making mischief on earth and bloodshed). He knows that the creation of Adam on earth constitutes a vital interest to life on earth, since He will send Prophets and Messengers from among the offspring of Adam .
In addition, there will be the righteous, worshippers, scholars, lovers of Allah and followers of His Messengers (Sallallahu Alaihi wa Sallam).
Allah knows best.