Answer 1

You can assign values of any type to var but after you have declared it you can't change the type.

var a = "string";
a = 9 //Error. You cant store integers to string type.

object type can hold any type of data.
But you can't add value to it before you declare it.

object a;
a = "string";

You can also store any type of data in to dynamic variable

dynamic a = "string";

The difference between object and dynamic is that the type checking on object happens on the compile time and on dynamic it happens on runtime.