Which of the following function sets first n characters of a string to a given c

Which of the following function sets first n characters of a string to a given character?

2) What is the output of this C code?

#include <stdio.h>
     int main()
     {
         char *str = "hello";
         char str1[5];
         strcpy(str, str1);
         printf("%s", str1);
     }

3) What will be the output of the program ?

 #include<stdio.h>
 int main()
 {
     printf(2+"C Programming MCQ on Study 2 Online\n");
     return 0;
 }

4) What is the output of this C code?

#include <stdio.h>
     int main()
     {
         char *str = "hello, world\n";
         printf("%d", strlen(str));
       }

5) What is the output of this C code?

#include <stdio.h>
     int main()
     {
         char *str = "hello, world";
         char *str1 = "hello, world";
         if (strcmp(str, str1))
             printf("equal");
         else
             printf("unequal");
     }