Questions

This is a layer of atmosphere about 60 to 70 km above the earth and extends to about 400km. It contains ionised particles which can reflect radio waves making radio communication round the world possible.

The Qatar Airways has launched the World’s longest scheduled commercial service to ply between Doha to Auckland. The inaugural service of Flight QR920 took off on February 5, 2017 from Doha and will take 16 hours and 20 minutes to travel 14,535 kilometers to reach Auckland in New Zealand.
This makes Qatar Airways to launch the World’s fastest and longest passenger service in terms of flying time. Prior to this, emirates launched the world’s longest non-stop scheduled commercial flight with a service from Dubai to Auckland, spanning 14,200 kilometres.

In computing, ".bak" is a filename extension commonly used to signify a backup copy of a file.

Without a word in it, it can't be called as song.