UPSC Prelims 2013 Environment & Ecology

Due to improper/indiscriminate disposal of old and used computers or their parts, which of the following are released into the environment as e-waste?
1. Beryllium
2. Cadmium
3. Chromium
4. Heptachlor
5. Mercury
6. Lead
7. Plutonium

Select the correct answer using the codes given below.