First, you mix the salt and sand with water, so the salt dissolves. Next, you filter the sand out, so you have the slat water and sand separated. Then, you evaporate the water, leaving the salt behind.
The formula for mole fraction is:
-(1)
The solubility of oxygen gas = 1.0 mmol/L (given)
1.0 mmol/L means 1.0 mmol are present in 1 L.
Converting mmol to mol:
So, moles of oxygen = 0.001 mol
For moles of water:
1 L of water = 1000 mL of water
Since, the density of water is 1.0 g/mL.
So, the mass of water is 1000 g.
Molar mass of water = 18 g/mol.
Number of moles of water = 
Substituting the values in formula (1):
Hence, the mole fraction is 
.
Answer:
1. (a) on land and offshore
2. (c) Boiling, evaporation and condensation
3.(d) Haematite and asphalt.
4. (a) octane
5.(d) petroleum gases, liquids and solids.
Explanation:
Cracking refers to the the breakdown of heavier fractions of crude oil to give the lighter fractions of crude oil having greater economic value. For instance, diesel oil may be cracked to yield gasoline which is composed of lighter hydrocarbons and has greater economic value. Cracking is of importance in the petroleum industry because it is used to produce lighter hydrocarbons from heavier ones.
Reforming is the conversion of straight chain hydrocarbons to branched chain hydrocarbons having a lesser tendency towards knocking of engines. It is very important in the petroleum industry because it leads to the production of better quality fuels with higher octane rating.
b) In Nigeria, oil producing communities are usually faced with the problem of damage to arable land due to oil exploration activities. Many oil producing communities in Nigeria are facing severe damage to the ecosystem due to oil drilling in those areas. Also, oil rich communities are at risk of crud oil spillage which contaminates water bodies and leads to loss of employment for the local people and death of aquatic animals.
They all have a certain amount of protons electrons and neutrons.
When a nucleus emits a positron, its atomic number is lowered by one but its mass number stays the same.
