Where does bitcoin whitepaper talk about blocksize 1 mb

What is the maximum size of a block in blockchain?

Perhaps more importantly, it also represented an effective block size limit increase: Bitcoin blocks now have a theoretical maximum size of 4 megabytes and a more realistic maximum size of 2 megabytes. The exact size depends on the types of transactions included.

How long is a block on blockchain?

In cryptocurrency, this is practically when the transaction takes place, so a shorter block time means faster transactions. The block time for Ethereum is set to between 14 and 15 seconds, while for bitcoin it is on average 10 minutes.