1. What is a product of petroleum used in dry cleaning? 2. What is a complex mixture of solid, liquid and gaseous hydrocarbons?

3. a) Define refining of petroleum.
b) What are the various products obtained from refining of petroleum? Write one use for each.

4. List the different types of coal with their carbon content and give one use for each.

5. What do you understand by global warming? Give any two consequences of global warming.​

The content of manganese (mn) in steel was determined spectrophotometrically and with the use of the standard addition method. an unknown sample of mn from a digested steel sample gave an absorbance of 0.185 when analyzed spectrophotometrically. when 5.00 ml of solution containing 95.5 ppm mn was added to 50.0 ml of the unknown steel solution (digested sample), the absorbance was 0.248. calculate the concentration, in parts-per-million (ppm), of mn in the digested steel sample solution.