using System;

using System.Xml;

using System.Xml.Linq;

using System.Linq;

public class Program

{

    public static void Main()

    {

        string xml=@"<MyRoot>

    <c1>0</c1>

    <c2>0</c2>

    <c3>0</c3>

    <c4>0</c4>

    <c5>1</c5>

    <c6>0</c6>

    <c7>0</c7>

    <c8>0</c8>

</MyRoot>";

        XDocument Doc = XDocument.Parse(xml);

         var nodes = from response in Doc.Descendants()

                     where response.Value == "1" 

                     select new {Name = response.Name, Value = response.Value };

        foreach(var node in nodes)

              Console.WriteLine(node.Name + ":  " + node.Value);

    }

}