I have Intel Core i5-4210U CPU in my laptop but memory is only 4GB. So, I am planning to upgrade to 16GB. As per product specifications, is shows Max 16Gb supported on i5-4210U but wanted to check if it can support single 16gb slot as my laptop got only one memory slot.
Your processor can support up to 16GB memory. You can find the memory specifications here:
However, you need to be concerned what your laptop motherboard will support. Your best answer will come from them.
When the 4th gen processors were rolling out, the largest SODIMM size available was 8GB. Without a BIOS Update that specifically adds support for the 8Gb memory technology that is necessary to create 16GB SODIMMs, it is unlikely that one will work.