C++ PROGRAMMING

Given the declaration:

int num1, num2;

int *ptr1;

int *ptr2;

double *ptr3;

Mark the following the statements as Valid or Invalid. If it is invalid, explain why

a. ptr1 = &num1;

b. ptr1 = ptr2;

c. ptr3 = ptr2;

d. num1 = ptr1;

e. ptr1 = &ptr2;

f. num1 = *ptr3;