You are in a gray zone, this code is unpredictable and will depend on your compiler.
A C compiler id allowed to rewrite your code as it see fit.
Depending on your compiler, your code
int k=25;
printf("\n %d %d %d",k==25,k=50,k>10);
can translate to (I have rewritten the code with 1 operation per line to illustrate the compiler work)
int k=25;
printf("\n %d",k==25);
k=50;
printf(" %d",k); printf(" %d",k>10);
or in your case
int k=25;
k=50;
printf("\n %d",k==25);
printf(" %d",k); printf(" %d",k>10);
In C, never use a variable more than once in a line if you also change its value.