Answer: I disagree. Elements form all pure substances, but some pure substances include elements bonded together to form molecules and compounds.
Explanation:
Pure substances are those that have a uniform and constant (invariable) composition.
That condition is met by both elements and compounds.
Elements are pure substances of one only kind of atoms. For example, gold, oxygen, sodium, hydrogen, are pure substances that arer elements. There are 118 elements known and they are all listed in the periodic table.
Compounds are pure substances formed by two or more different kind of atoms. Water (H₂O), table salt (NaCl), and ethanol (CH₃-CH₂OH), are examples of pure substances that are compounds. There are pratically infinite different compounds.
In conclusion, compounds are also pure substances, since every sample of a given compound has always the same kind of elements bonded in the same way.
The statement labeled as (a) is the correct one on that list.
Answer:
Mass = 16.4 g
Explanation:
Given data:
Mass of K = 8.50 g
Mass of KCl produced = ?
Solution:
Chemical equation:
2K + Cl₂ → 2KCl
Number of moles of K:
Number of moles = mass/ molar mass
Number of moles = 8.50 g/ 39 g/mol
Number of moles = 0.22 mol
Now we will compare the moles of potassium and potassium chloride.
K : KCl
2 : 2
0.22 : 0.22
Mass of KCl:
Mass = number of moles × molar mass
Mass = 0.22 mol × 74.55 g/mol
Mass = 16.4 g
Answer: a) Temperature of 
b) 
c) dehydrating agent
Explanation:
Ethanol is heated with an excess of concentrated sulfuric acid at a temperature of 170°C to produce ethene.
The balanced chemical reaction is:
Here concentrated sulfuric acid removes a water molecule from ethanol and thus acts as a dehydrating agent.
Answer:
84%
Explanation:
Fossil Fuels Supply 84 Percent Of Worlds Electricity
