Which of the following cannot be checked in a switch-case statement?

Which of the following cannot be checked in a switch-case statement?

2) What is the output of this C code(When 1 is entered)?

#include <stdio.h>
     void main()
     {
         int ch;
         printf("enter a value btw 1 to 2:");
         scanf("%d", &ch);
         switch (ch)
         {
         case 1:             printf("1\n");
         default:             printf("2\n");
         }
     }

3) A switch statement is used to:

4) What is the output of this C code?

#include <stdio.h>
     int main()
     {
         float f = 1;
         switch (f)
         {
         case 1.0:             printf("yes\n");
             break;
         default:             printf("default\n");
         }
     }

5) What is the output of this C code?

#include <stdio.h>
     int main()
     {
         switch (printf("Do"))
         {
         case 1:             printf("First\n");
             break;
         case 2:             printf("Second\n");
             break;
         default:             printf("Default\n");
             break;
         }
     }