Class 11 | Chemistry | Chapter 14 | Environmental chemistry
In which of the following regions hydrogen and helium are found : (a) Stratosphere (b) Mesosphere (c) Exosphere (d) Troposphere
Class 11 | Chemistry | Chapter 14 | Environmental chemistry
![Air (Prevention and Control of Pollution) Act was amended in 1987 to include among pollutants 1. Vehicular exhaust 2. Allergy causing pollen 3. Noise 4. Particulates of size 2.5 micrometer or below [NEET 2020 ]](https://blogger.googleusercontent.com/img/a/AVvXsEjh5KIsSo4NuEdZ0goPPYnXPM5lPbE-QzB5I729-0GbhgkSB3k8GDfBtO1MDA1ftgBUwHmAnb6OMlQOw6txCdidIRQinj3WCTbmpefUagCTY2cF4PqJttewIziy0EFe1LzAFi6c05ddYwq6qQ2gjo92QgYNy5_0hgIu1E_FBuPf0iM4c0HAgGW5wc4IyQ=w74-h74-p-k-no-nu)
