Now Google has launched a new App - Google Opinion Rewards in the Play Store, which will send Surveys to the installed Smartphones and Fill Up those Surveys, which gives the App User the Play Store Credits. Those Credits rupees you can use in the Play Store in Apps or Games.
Just download Google Opinion Rewards from Google Play Store. After that you will send more than this App Surveys.
On completing those surveys, Google will give you some money that you can spend in your Google Play Store. So it’s very useful and easy to earn money.