Persist RadioButton Settings (C#)

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
            private int BitPosition = 1;
            private int BitMask = 0;

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            foreach(RadioButton RadioButton in groupBox1.Controls.OfType<RadioButton>())
            {   // add RadioButtonSelected setting to this project
                BitMask = Properties.Settings.Default.RadioButtonSelected;
                RadioButton.Tag = BitPosition;
                RadioButton.Checked = (BitMask & Convert.ToInt32(RadioButton.Tag)) == Convert.ToInt32(RadioButton.Tag);
                BitPosition *= 2;
            }
        }

        private void Form1_FormClosing(object sender, FormClosingEventArgs e)
        {
            RadioButton checkedRadioButton = groupBox1.Controls.OfType<RadioButton>().FirstOrDefault(r => r.Checked);

            BitMask = 0;
            BitMask = BitMask ^ Convert.ToInt32(checkedRadioButton.Tag);
            Properties.Settings.Default.RadioButtonSelected = BitMask;
            Properties.Settings.Default.Save();
        }
    }
}