You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <allpages apcontinue="B4.8051_Interfacing_Gas_Sensor(MQ6)" />
  </query-continue>
  <query>
    <allpages>
      <p pageid="501" ns="0" title="B0.8051 Interfacing GPS" />
      <p pageid="2298" ns="0" title="B0.PIC Interfacing GPS" />
      <p pageid="507" ns="0" title="B1.8051 Interfacing Bluetooth HC05" />
      <p pageid="504" ns="0" title="B1.8051 Interfacing GPS" />
      <p pageid="606" ns="0" title="B1.PIC Interfacing Bluetooth HC05" />
      <p pageid="2524" ns="0" title="B2.8051 Interfacing Zigbee" />
      <p pageid="609" ns="0" title="B2.PIC Interfacing Zigbee" />
      <p pageid="2551" ns="0" title="B3.8051 Interfacing Relay" />
      <p pageid="1883" ns="0" title="B3.AVR Interfacing Relay" />
      <p pageid="612" ns="0" title="B3.PIC Interfacing Relay" />
    </allpages>
  </query>
</api>