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Secondary 1 | Maths
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Please!! Help me !!
Date Posted: 4 years ago
Views: 409
HF is a compound, made of two different elements hydrogen (H) and fluorine (F) chemically combined together.
A compound does not always have properties of its respective elements. They are different. Sodium, chlorine and sodium chloride have different characteristics altogether, for example. So the first statement is not necessarily true.
A compound can be formed by chemical processes such as combustion. A notable example of this is carbon reacting with oxygen to form carbon dioxide. So the second statement is true.
A compound, however, cannot be formed by physical processes (such as boiling or cutting). So the third statement is false.
A compound needs to be made of two or more different elements chemically combined together. Percentage composition will depend on the compound formed. So the last statement is not necessarily true, but I have not come across any compound with the same composition by mass so far so I do not have any evidence to disprove the last statement.
Edit: Sulphur dioxide, SO2, is approximately 50% sulphur by mass.
A compound does not always have properties of its respective elements. They are different. Sodium, chlorine and sodium chloride have different characteristics altogether, for example. So the first statement is not necessarily true.
A compound can be formed by chemical processes such as combustion. A notable example of this is carbon reacting with oxygen to form carbon dioxide. So the second statement is true.
A compound, however, cannot be formed by physical processes (such as boiling or cutting). So the third statement is false.
A compound needs to be made of two or more different elements chemically combined together. Percentage composition will depend on the compound formed. So the last statement is not necessarily true, but I have not come across any compound with the same composition by mass so far so I do not have any evidence to disprove the last statement.
Edit: Sulphur dioxide, SO2, is approximately 50% sulphur by mass.
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Both are B, and in the second question, option D doesnt make sense
Thnks
Last one would have been a valid statement (all compounds are made of two or more elements chemically combined together and the vast majority of compounds have different percentage by mass for each element), but then SO2 spoils this.
There is a missing 'is' in option D.
Another option is barium titanate, BaTiO3, where the titanium has atomic mass 48 (main isotope) and 3 oxygen ions each with atomic mass 16 (main isotope)
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