1.   What is kernel?

2.   Is Linux an operating system or a kernel?

3.   Is Linux Operating System Immune to Malware?

Ans 1: Kernel is core component of an operating system. Kernel acts as a bridge between applications and data processing performed at hardware level using inter-process communication and system calls.

Ans 2: Linux is just a kernel not an operating system. However the term Linux is often referred to a complete operating system that includes a shell  and command line and/or GUI tools to control the system.

Ans 3: One reason people switch to Linux is to have better security. Once you switch to Linux, the thinking goes, you no longer have to worry about viruses and other types of malware. But while this is largely true in practice, desktop Linux isn't actually all that secure.