c programs for these, not any other Language

Write Programs of the Following (a) Write a function to calculate the factorial value of any integer entered through the keyboard. (b) Write a function power ( a, b ), to calculate the value of a raised to b. (d) Any year is entered through the keyboard. Write a function to determine whether the year is a leap year or not. (e) A positive integer is entered through the keyboard. Write a function to obtain the prime factors of this number. For example, prime factors of 24 are 2, 2, 2 and 3, whereas prime factors of 35 are 5 and 7