What attribute makes a radio button or checkbox input selected?

checked="checked" selected="selected" disabled="disabled"

<input type="checkbox" name="a_name" value="value" checked="checked" />

What CSS value scales the background image to the largest size contained within the element?

repeat-x contain linear-gradient

#id {
  background:url("path_to_image.png");
  background-size:contain;
  background-repeat:no-repeat;
}

What operator is used to determine the rest of the division of two numbers?

% * /

var rest8_7 = 8 % 7;
alert(rest8_7);

Indicate the PHP function that rounds a number up to the next highest integer.

floor() ceil() abs()

$nr = ceil(3.5);
echo $nr;        // 4

Jquery/jquery Course