I know I'm super late to answering this because it's a two week old question, but I'll just answer it any way lol.
The main reason why modern chemistry is considered scientific is because to confirm their results, scientists use the scientific method.
Answer:
- <em>Chemical equations are balanced </em><u>to comply with the law of conservation of mass.</u>
Explanation:
Law of conservation of mass states that matter cannot be either created or destroyed.
A skeleton chemical equation shows the reactants and products of a chemical reaction without taking into account the real proportion in which the reactants combine and the products are obtained.
An example of a skeleton reaction is the combustion of methane:
Such as that equation is shown, there are four atoms of hydrogen in the reactants but only 2 atoms of hydrogen in the products. Also, there are 2 atoms of oxygen in the reactants but three atoms of oxygen in the products. This seems to show that some atoms of hydrogen have been destroyed and some atoms of oxygen have been created. This is impossible as it is against the law of conservation of matter.
Then, to show a real situation, the chemical equation of combustion must be balanced, adjusting the coefficients. This is the balanced chemical equation:
Now you see that the number of atoms of each matter is conserved: the number of carbon atoms in each side is 1, the number of atoms of hydrogen in each side is 4, and the number of atoms of oxygen in each side is 4. Thus, by balancing the chemical equation, the law of conservation of mass is not violated.
Answer:- D. Double- replacement reaction
Explanations:- In general, the decomposition reactions looks like:
The given reaction looks different than this and so it is not decomposition reaction.
A single-replacement reaction looks like:
Our reaction looks different from this so single-replacement is also not correct.
Synthesis reaction looks exactly opposite to decomposition reaction.
The given reaction is different than this and so it is not synthesis reaction also.
A double-replacement reaction looks like:
In this reaction, the ions are exchanged as could be seen in the general reaction. On reaction side,A is with B and C is with D. On product side, A is with D and C is with B.
The same is happening in the given reaction. Nitrate ion is with lead metal on reactant side and chlorine is with hydrogen, On product side, Chlorine is with lead metal and nitrate ion is with hydrogen. So, ion exchange has taken place here and so this is a double-replacement reaction and choice D is correct.
B. False. It is banned worldwide for agricultural uses. The <span>use of DDT is still authorized in small proportions in countries that need it, with support deployed for the alteration to safer and more effective alternatives.</span>
