Write down the C code for the following questions.a) Write a program in C to check if a given number is even or odd using the function.b) Write a program in C to swap two numbers using a function.c) Write a program in C to find the square of a number using the function.d) Write a program in C to find the factorial of a number using the function.e) Write a program in C to calculate the area of circle using the function.f) Write a C program to compute the sum of the first “N” natural numbers using thefunction.g) Write a program in C to print the Fibonacci series using the function.

Sure, here are the C code for the questions:

a) Check if a number is even or odd:

#include <stdio.h>
void check(int num) {
    if(num % 2 == 0)
        printf("%d is even.", num);
    else
        printf("%d is odd.", num);
}
int main() {
    int num;
    printf("Enter a number: ");
    scanf("%d", &num);
    check(num);
    return 0;
}

b) Swap two numbers:

#include <stdio.h>
void swap(int *num1, int *num2) {
    int temp;
    temp = *num1;
    *num1 = *num2;
    *num2 = temp;
}
int main() {
    int num1, num2;
    printf("Enter two numbers: ");
    scanf("%d%d", &num1, &num2);
    printf("Before swapping: %d, %d\n", num1, num2);
    swap(&num1, &num2);
    printf("After swapping: %d, %d", num1, num2);
    return 0;
}

c) Find the square of a number:

#include <stdio.h>
int square(int num) {
    return num * num;
}
int main() {
    int num;
    printf("Enter a number: ");
    scanf("%d", &num);
    printf("Square of %d is %d", num, square(num));
    return 0;
}

d) Find the factorial of a number:

#include <stdio.h>
int factorial(int num) {
    if(num == 0)
        return 1;
    else
        return num * factorial(num - 1);
}
int main() {
    int num;
    printf("Enter a number: ");
    scanf("%d", &num);
    printf("Factorial of %d is %d", num, factorial(num));
    return 0;
}

e) Calculate the area of a circle:

#include <stdio.h>
#define PI 3.1416
float area(float radius) {
    return PI * radius * radius;
}
int main() {
    float radius;
    printf("Enter the radius of the circle: ");
    scanf("%f", &radius);
    printf("Area of the circle is %.2f", area(radius));
    return 0;
}

f) Compute the sum of the first “N” natural numbers:

#include <stdio.h>
int sum(int num) {
    return num * (num + 1) / 2;
}
int main() {
    int num;
    printf("Enter a number: ");
    scanf("%d", &num);
    printf("Sum of first %d natural numbers is %d", num, sum(num));
    return 0;
}

g) Print the Fibonacci series:

#include <stdio.h>
void fibonacci(int num) {
    int t1 = 0, t2 = 1, nextTerm;
    for (int i = 1; i <= num; ++i) {
        printf("%d, ", t1);
        nextTerm = t1 + t2;
        t1 = t2;
        t2 = nextTerm;
    }
}
int main() {
    int num;
    printf("Enter the number of terms: ");
    scanf("%d", &num);
    fibonacci(num);
    return 0;
}