Answer:
C but read the limitation
Explanation:
Gold sample
Color wouldn't tell you much. In fact it may fool you. Fool's Gold is the same color as gold.
Gold is very malleable. That's what hitting gold with a hammer will do. It tends to shape the gold without destroying it into lots of pieces. A lot of yellow things have that property.
If only it was that simply. Yes if you are sure there is gold in that location. You have to pick this answer, because the other 2 don't work. So this is possible, but not the best way. The best way is to subject the sample to chemical treatment. If you are left with a yellow sample, then you could make the case for it being gold.
Answer: For 
, 
is the oxidizing agent and 
is the reducing agent.
For 
, Mg is the reducing agent and 
is the oxidizing agent.
Explanation:
An oxidizing agent is defined as the substance which tends to oxidize other substances by itself gaining electrons. As a result, there will occur a decrease in its oxidation state.
On the other hand, a substance which tends to reduce other substances by itself losing electrons is known as an reducing agent. There will occur an increase in oxidation state of a reducing agent.
For example,
Oxidation: 
Reduction: 
Hence, here is the oxidizing agent and is the reducing agent.
Also,
Oxidation: 
Reduction: 
Hence, here Mg is the reducing agent and is the oxidizing agent.
Answer:
Add decanoic acid. Another way to separate salt and water is via chemical reaction. For instance, research has shown that treating salt water with a chemical called decanoic acid is a reliable way to remove the salt.
Answer:
Metalloids elements whose properties are intermediate between those of metals and solid nonmetals or semiconductors.
Some examples:
Chemical element.
Boron.
Semiconductor.
Arsenic.
Silicon.
Selenium.
Antimony.
Germanium.
