using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var teste = new Dictionary<string, object>();

        teste.Add("chave1", 1);

        teste.Add("chave3", 2);

        var chave1 = teste.FirstOrDefault(x => x.Key == "chave1").Value;

        Console.WriteLine("chave1 = " + chave1);

        var chave3 = teste.FirstOrDefault(x => x.Key == "chave3").Value;

        Console.WriteLine(chave3 == null ? "chave3 nula" : "chave3 = " + chave3);

    }

}