Edit in JSFiddle

var myApp = angular.module('myApp', []);


myApp.controller('Ctrl', myController);
      
myController.$inject = ['$scope']
   function myController($scope) {
    $scope.list = [  
        {"name": "Item 1", "disposition": "true"},  
        {"name": "Item 2", "disposition": "false"},  
        {"name": "Item 3", "disposition": "true"},  
        {"name": "Item 4", "disposition": "false"},  
        {"name": "Item 5", "disposition": "true"}
    ];
$scope.selectedIndex = 5;
};


<div ng-controller="Ctrl">  
<ul>
    <li ng-class="{green: $index==selectedIndex}" ng-repeat="item in list"> <!--apply "green" class to the 3er element -->
       {{item.name}}
    </li>
</ul>
</div>
.green{
    color: green;
}

External resources loaded into this fiddle: