I think that the answer might be B.
Sodium chloride is made from one sodium atom and one chlorine atom:
Sodium has a charge of +1, or just +.
Chlorine has a charge of -1, or just -.
These balance out.
Answer: The correct option is C ( is very hard and burns cleanly).
Explanation:
COAL is a form of rock that is made up of mostly carbon amongst other elements which includes sulphur, nitrogen, hydrogen and oxygen. There are different types of coal which include:
--> anthracite ( 90% carbon)
--> bituminous coal ( 70-90% carbon)
--> lignite ( 60- 70% carbon) and
--> peat (60 % carbon).
Anthracite is the type of coal that contains the highest carbon content ( 90% carbon). This makes it very hard and is often a times referred to as HARD COAL. Anthracite is a higher quality coal for domestic and open fire heating. This is because it contains less impurities than other type of coal and thereby making it to BURN CLEANLY avoiding atmospheric pollution.
