How many transactions are in a single block? This is not a question that we can answer with a simple yes or no answer. There are so many factors that can make a difference, and if you know the different ways that transactions can occur in a block, then you can probably answer that question. Let’s assume for a moment that transactions occur in a single block with a fixed size.
When a transaction occurs, one of three things could happen. First, the transaction could be a softfork, in which case the new transaction can be included into the main chain with little modification. Second, hardcore, which is when the new transaction gets immediately rejected by miners and then added into the main chain by miners who have upgraded to that particular protocol; or third, a fork where miners choose to ignore the new transaction and add it to the main chain later on.
If you are looking for how many transactions are in a single block, then softfork blocks are not too hard to figure out. The reason why the softfork blocks are called softfork blocks is because they only include transactions that were successfully created by mining nodes, meaning the entire transaction had to be accepted by nodes before it would get mined. If a softfork blocks contain an illegal transaction, then the entire transaction would be ignored and it wouldn’t be valid on the network at all.
On the other hand, the hardcore blocks would also contain a transaction that was not accepted by mining nodes, and therefore if you wanted to create such a transaction, you would have to break a rule and add it to the main chain and get it approved there. With a hardfork block, you can create an illegal transaction and you can then add it to the main chain as well.
As you can see, there are two types of blocks. A softfork will include an illegal transaction, while a hardcore block would not. There is also a forkblock, which is a block that doesn’t have a main chain anymore, but instead has an alternate branch, which is still a part of the main chain. Each of these types of blocks has a different limit of how many transactions can be made in a block and has a different rate of how fast they can happen.
So now that we understand how many transactions are in a hardcore block, we can figure out how many transactions can be made in a soft fork block. In a softfork, transactions are only allowed to happen during a time frame in which the network sees that a certain rule of the network was broken. For example, if a network sees that a certain rule is being broken and a majority of nodes are reporting that rule as broken, then the softfork becomes invalid. It would be invalid because the transaction will be rejected and the nodes that are reporting that rule as broken will close the block. However, if that block had been closed before, then the transaction would not be considered invalid.