I have a a requirement that when priview button on the 1st vf page is clicked then the corresponding information of the record for which the button is pressed should be displayed on a new vf page. but it is not working properly.. my code is:
Ist vf page:
<apex:page standardController="FeedbackMain__c" extensions="FeedbackMainlistController">
<apex:form>
  <apex:pageBlock >
  <apex:pageBlockTable value="{!feed}" var="a" rowClasses="oddrow,evenrow,dataTableRow" styleClass="fontfamily" id="Details1" style="width:40%;">
            <apex:column headerValue="Feedback Number" style="width:10%;">
            <apex:outputField value="{!a.Name}"/> <br></br>
        </apex:column>
         <apex:column headerValue="Feedback Preview" style="width:35%;" >
            <input type="button" onclick="{!queslist}" value="Preview" style="width:35%;"/>
            </apex:column>
  </apex:pageBlockTable>
  </apex:pageBlock>
  </apex:form>
</apex:page>
controller:

public class FeedbackMainlistController
{
  Public Id qid{get;set;}
    public FeedbackMainlistController(ApexPages.StandardController controller) {
       qid=controller.getId();
    }
    public List <FeedbackMain__c>queslist;
    public List<FeedbackMain__c> showQues;
    public List<FeedbackMain__c> feed;
    public List<FeedbackMain__c> getFeed()
 {
feed=[SELECT id,name,Feedback_Name__c FROM FeedbackMain__c];
return feed;


 }
  public pageReference queslist()
  {
  
    //showQues=[SELECT Related_Question_Bank__r.Name FROM FeedbackMain__c where id=:qid];
    PageReference P = new PageReference('https://c.cs20.visual.force.com/apex/FeedbackQuestionMain');
    p.setRedirect(true);
    return p;
  }
}

2nd vf page:
<apex:page standardController="FeedbackMain__c" extensions="FeedbackMainlistController">> <apex:pageBlock > <apex:pageBlockTable value="{!feed}" var="a" rowClasses="oddrow,evenrow,dataTableRow" styleClass="fontfamily" id="Details1" style="width:40%;"> <!-- <div id="{!a.Id}" class="hideshow{!a.Id}">--> <apex:column headerValue="Feedback Question" style="width:10%;"> <div id="{!a.Id}" class="hideshow{!a.Id}"> <apex:outputField value="{!a.Related_Question_Bank__r.Name}"/> <br></br> </div> </apex:column> </apex:pageBlockTable> </apex:pageBlock> </apex:page>