What is a Central Bank Digital Currency or "CBDC", what is the current world status of CBDC's and what should we know about them in terms of potential benefits and likely risks and policy considerations (hint; refer to the Federal Reserve WP for some of the answers)?  

Include in your answer if you think CBDC's are a good thing or a bad thing and why. What are the financial service and risk implications of crypto assets, especially stable coins?

A Blockchain operates as a decentralized system usually using either POW or POS for consensus approvals, explain how consensus protocols work and what some of the tradeoffs of alternative consensus algorithms - proof-of-work, proof-of- stake are.  

In your answer explain what happens if a malicious agent tries to gain majority control over the hash rate (known as a 51% attack), how has this worked in the past and is it possible to protect against this attack and how?