I was solving this challenge and my VF code is:

<apex:page standardController="Account" recordSetVar="Accounts" >
    <apex:pageblock>
        <apex:repeat var="a" value="{!Accounts}" rendered="true"  id="account_list">
            <li>
                <apex:outputLink value="https://ap1.salesforce.com/{!a.ID}" >
                    <apex:outputText value="{!a.Name}"/>
                </apex:outputLink>
            </li>
        </apex:repeat>
    </apex:pageblock>
</apex:page>

I am getting the list of accounts as required and on clicking on any of the accouts, it redirects to that accounts detail page.
Still I am getting following error from trailhead:

"The page does not bind to the record ID value (in order to link to the record detail page)"

Hi all,

I have been planning to write my certification for admin(201) next month.
Would appreciate if you guys could guide me abt material that would be most helpful in this regards

Thanks

Cheers!