What is the Bharat Stage $II$ equivalent to?

Which measures can be taken to control noise pollution?
$I-$ Use of sound-absorbent materials or mufflers in industries.
$II-$ Creating horn-free zones around hospitals and schools.
$III-$ Setting permissible sound levels for firecrackers and loud speakers.
$IV-$ Restricting the use of loudspeakers after a certain time.

Photochemical smog pollution does not contain

The addition of elements like nitrogen and phosphorus to a lake through streams leads to:

What is the intensity of sound in normal conversation?

Carbon monoxide $(CO)$ is a pollutant because it: