use Generic List the Easy way
vcon.Open();
SqlCommand cmd = new SqlCommand("select question from examQuestion where tchId='123'", vcon);
SqlDataReader dr = cmd.ExecuteReader();
System.Collections.Generic.List<string> LstQuestion = new System.Collections.Generic.List<string>();
while (dr.Read())
{
LstQuestion.Add(dr.GetString(0));
}
vcon.Close();