Questions

Because of high stability, large Q (Quality Factor) & the frequency that doesn't drift with aging. Crystal is used as a clock source most of the times.

One word substitute for "That which cannot be heard" is Inaudible.

Vistadome coach train flagged off in April 2017 is routed between Visakhapatnam to Araku valley station.

Carbon monoxide is one of the major pollutant present in the world. The six most common pollutants include ozone, carbon monoxide, sulfur dioxide, lead, nitrogen oxides, and particulate matter.

Carbon monoxide is a common atmospheric pollutant. It is produced largely in combustion processes like in industries and in vehicles. It is a gas that cannot be seen nor smelled.

Now a days, printers we are using are called as laser printers. The speed of a laser printer is measured in PPM i.e, Pages Per Minute. 

Laser printing is an electrostatic digital printing process. It produces high-quality text and graphics by repeatedly passing a laser beam back and forth over a negatively charged cylinder called a "drum" to define a differentially charged image.

Compared to inkjet printers which use ink for printing laser printers are more expensive as they use toner which lasts for long.