Is it possible to store mixed datatypes such as int, string, float, char, all in one array?

Yes, using a dynamic or object type array

dynamic[] arr = { “abc”, 11, 11.23, true };
Console.WriteLine(arr[0] + “ “ + arr[1] + “ “ + arr[2] + “ “ + arr[3]);

        ArrayList dynamicArray = new ArrayList(4);
        dynamicArray.Add("abc");
        dynamicArray.Add(11);
        dynamicArray.Add(12.34);
        dynamicArray.Add(true);
        Console.WriteLine(dynamicArray[0] + " " + dynamicArray[1] + " " + dynamicArray[2] + " " + dynamicArray[3]);

yes,we can declare the array as an object type
example :-
object[] ar = { 22, ‘h’, “All” };

Yes , we need to create array as an object type or we need to create aarayList.