See if bootstrap checkbox is checked asp.net c#

See if bootstrap checkbox is checked asp.net c#

I need to get true or false if bootstrap check-box is checked on server side
This is the control:
<div id="CheckCategoria" runat="server" class="btn-group"
data-toggle="buttons-checkbox" runat="server">
<asp:Button ID="ChkInspecao" OnClientClick="return
false;" Text="Inspeção" UseSubmitBehavior="False"
runat="server" CssClass="btn btn-check" />
<asp:Button ID="ChkHipot" OnClientClick="return
false;" Text="Hipot" UseSubmitBehavior="False"
runat="server" CssClass="btn btn-check" />
<asp:Button ID="ChkCalibracao"
OnClientClick="return false;" Text="Calibração"
UseSubmitBehavior="False" runat="server"
CssClass="btn btn-check" />
<asp:Button ID="ChkChecagemInterna"
OnClientClick="return false;" Text="Checagem
Interna" UseSubmitBehavior="False"
runat="server" CssClass="btn btn-check" />
<asp:Button ID="ChkRevisao"
OnClientClick="return false;" Text="Revisão"
UseSubmitBehavior="False" runat="server"
CssClass="btn btn-check" />
</div>
as they have runnat="sever", I can get them on server-side but how can I
see if it's toggled or not?
I tried:
string Inspecao = ChkInspecao.Attributes["checked"];
but it's returning null.
how can I do that?