Find account attributes based on account Id using SOAP request MS CRM 2011 and MS CRM 2013

I need to retrieve all the attribute from account entity based on  accountID.

sample code given below:

 function ExecuteRequest(_XML, Message) {

try {

var _ResultXML = null;

var xmlhttp = new XMLHttpRequest();

xmlhttp.open("POST", Xrm.Page.context.getServerUrl() +"/XRMServices/2011/Organization.svc/web", false);

xmlhttp.setRequestHeader("Accept", "application/xml, text/xml, */*");

xmlhttp.setRequestHeader("Content-Type", "text/xml; charset=utf-8");

xmlhttp.setRequestHeader("SOAPAction","http://schemas.microsoft.com/xrm/2011/Contracts/Services/IOrganizationService/" + Message);

xmlhttp.send(_XML);

_ResultXML = xmlhttp.responseXML;

var errorCount = _ResultXML.selectNodes('//error').length;

if (errorCount != 0) {

var msg = resultXml.selectSingleNode('//description').nodeTypedValue;

alert(msg);

_ResultXML = null;

return _ResultXML;

}

else {

return _ResultXML;

}

}

catch (Err) {

alert(Err);

return;

}

}

function GetAccountName(accountID) {

var request = "<s:Envelope xmlns:s='http://schemas.xmlsoap.org/soap/envelope/'>" +
"<s:Body>" +
"<Retrieve xmlns='http://schemas.microsoft.com/xrm/2011/Contracts/Services' xmlns:i='http://www.w3.org/2001/XMLSchema-instance'>" +
"<entityName>account</entityName>" +
"<id>"+ accountID +"</id>" +
"<columnSet xmlns:a='http://schemas.microsoft.com/xrm/2011/Contracts'>" +
"<a:AllColumns>false</a:AllColumns>" +
"<a:Columns xmlns:b='http://schemas.microsoft.com/2003/10/Serialization/Arrays'>" +
"<b:string>name</b:string>" +
"<b:string>accountnumber</b:string>" +
"</a:Columns>" +
"</columnSet>" +
"</Retrieve>" +
"</s:Body>" +
"</s:Envelope>";
var _ResultXML = ExecuteRequest(request, "Retrieve");

var _AccountName = _ResultXML.selectSingleNode("//a:Attributes").selectSingleNode("//b:value").text;

return _AccountName;

}