1.1. Extended Only

When nitrogen dioxide is cooled, it forms a yellow liquid and then pale yellow crystals. These crystals are heated and the temperature is measured every minute. The following graph can be drawn.

i) Describe the arrangement and movement of the molecules in the region A–B.

 ii) Name the change that occurs in the region B–C

1.2. Extended Only

Nitrogen dioxide and other oxides of nitrogen are formed in car engines.

i) Explain how these oxides are formed.

 ii) How are they removed from the exhaust gases?

1.3. Nitrogen dioxide, oxygen and water react to form dilute nitric acid.

Describe how lead(II) nitrate crystals could be prepared from dilute nitric acid and lead(II) oxide.