Answer: The precipitate formed is 
Explanation:
A double displacement reaction is one in which exchange of ions take place. The salts which are soluble in water are designated by symbol (aq) and those which are insoluble in water and remain in solid or precipitated form are represented by (s) after their chemical formulas.
A double displacement reaction in which one of the product is formed as a solid is called as precipitation reaction.
The balanced chemical equation is:

Answer:
(d) 3,7-dimethyl-4-nonyne.
Explanation:
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In this case, considering the attached picture on which you can see that the main chain has nine carbon atoms, one tripe bond at the fourth carbon and two methyl radicals at the third and seventh carbons respectively, by following the IUPAC rules, the name would be: (d) 3,7-dimethyl-4-nonyne since the chain must start at the side closest to the first triple bond due to its priority and subsequently considering the present radicals.
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Weather refers to short term atmospheric conditions while climate is the weather of a specific region averaged over a long period of time. Climate change refers to long-term changes.
i. When an acid reacts with metal, a salt and hydrogen are produced:
ii. When oxygen and metal react, metal oxide forms also known as rust
iii. metal and water produce hydrogen gas