Answer:
Explanation:
Overuse of antibiotics leads to bacteria's resistance against our drugs. This is increasing at an alarming rate and the reason is that overuse of antibiotics kills bacteria that lack the "resistance" gene or gene that can help them survive the antibiotics (similar is the case for insects that die to insecticides). But, some bacteria can have random mutations in their gene that can help them survive the antibiotic (similar is the case for some insects that can survive the insecticide), thus the surviving bacteria give rise to next generation of bacteria that are resistant to the given antibiotic (similar to how insects that survive the insecticide give birth to new insects that are resistant to insecticide too). Soon, every generation adds new antibiotic resistant bacteria (or new insecticide resistant insects in the case of insects) which is dangerous for all of life on this planet. Therefore, both are similar in the sense that new generations of these organisms will be resistant to our weapons against them.
Answer:
228
Explanation:
alpha decay is removing alpha particle
2 number of protons, 4 mass number = 2 protons + 2 neutrons
We have
90 protons and 142 neutrons
- 2 protons - 2 neutrons
88 protons 140 neutrons
Mass number of new (daughter) atom = 88 +140 = 228
Answer:
Correct Answer: 228
Explanation:
alpha decay is removing alpha particle
2 number of protons, 4 mass number = 2 protons + 2 neutrons
________________________________________________
We have:
_______________________
90 protons and 142 neutrons
- 2 protons - 2 neutrons
88 protons 140 neutrons
Mass number of new (daughter) atom = 88 +140 = 228
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Answer: Option (c) is the correct answer.
Explanation:
According to the law of conservation of energy or matter, it is stated that energy can neither be created nor it can be destroyed. It can only be transformed from one form to another.
Same applies to the matter that matter can be transformed from one form to another.
Thus, we can conclude that during a chemical reaction both matter and energy is conserved.
Both energy and matter are conserved during a chemical reaction.
Further Explanation:
Chemical reaction
It is the process to convert one or more substances into different substances. Reactants are the substances that experience changes during chemical reactions whereas products are formed once the reaction is complete. The properties of products are usually different from those of reactants.
Law of conservation of mass:
According to this law, the mass of an isolated system can neither be created nor be destroyed in a chemical reaction. In other words, the mass of reactants will always be equal to the mass of products. The quantity of matter in any material is known as mass. The conservation of matter also holds good for chemical reactions.
Law of conservation of energy:
It states that the energy can neither be created nor be destroyed but can only be converted from one form to another.
Therefore both matter and energy are conserved during a chemical reaction.
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Answer details:
Grade: High School
Subject: Chemistry
Chapter: Basic concepts of chemistry
Keywords: chemical reaction, matter, mass, energy, conserved, created, destroyed, reactants, products, properties, different, isolated system.
Answer:
Explanation:
That is a chemical property of alkali metals: they are highly reactive and react vigorously with water to produce the correspondant hydroxide and hydrogen gas.
These are some of those reactions:
The alkali metals are the elements of group 1 of the periodic table: Li, Na, K, Rb, Cs, and Fr. They have one valence electron which may lose easily to form an ion with charge +1.
Alkali metals react with water to produce hydrogen gas and a basic solution of the metal hydroxide (for instance, sodium hydroxide when lithium is in the reaction). This reaction signifies the easier oxidation of alkali metals compared to hydrogen.
When alkali metals react with water, they form hydrogen gas and a basic solution of the metal hydroxide. This vigorous reaction reveals that alkali metals are easier to oxidize than is hydrogen. For instance, considering the reaction of lithium with water:
2Li(s) + 2H₂O(l) --> 2NaOH(aq) + H₂(g)
The solid state (s) lithium reacts with liquid water to generate hydrogen gas and the ionic compound sodium hydroxide. This sodium hydroxide, which is a solid in its pure form, promptly dissolves in water.
The same kind of reaction occurs with other alkali metals and also some alkaline earth metals, although beryllium and magnesium are exceptions.
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You can differentiate between sodium and calcium ions using sodium carbonate by observing a precipitation reaction. Sodium carbonate reacts with calcium ions to form a solid precipitate of calcium carbonate, while sodium ions remain in solution.
To differentiate between the sodium ion (Na+) and the calcium ion (Ca2+) in a solution of Na2CO3, a type of precipitation reaction can be used. Sodium carbonate (Na2CO3) can react with calcium ions (Ca2+) to form calcium carbonate (CaCO3) and 2 sodium ions (Na+), which is a precipitate reaction. This is because calcium carbonate is insoluble in water and will form a solid precipitate, while sodium ions will remain in solution.
The balanced reaction equation is: Na2CO3(aq) + Ca2+(aq) → CaCO3(s) + 2Na+(aq).
As the sodium continues to exist in the solution and does not form a precipitate, it can be differentiated from the calcium.
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c. stratosphere
b. mesosphere
d. exosphere
Answer: Option (c) is the correct answer.
Explanation:
A layer above the troposphere and below the mesosphere is known as stratosphere.
This layer of stratosphere contains about 90% concentration of ozone and there is no occurrence of weather in this layer.
The occurrence of ozone in stratosphere makes it warmer.
Therefore, we can conclude that the stratosphere contains the highest concentration of ozone.
(2) ethanol (4) water
The compound that has the lowest vapor pressure is ethanoicacid. The correct option is 1.
Vapor pressure is a measure of a material'stendency to change into a gaseous or vapor state, and it rises with temperature.
The boilingpoint of a liquid is the temperature at which the vapor pressure at its surface equals the pressure exerted by its surroundings.
A liquid with weak intermolecularforces evaporates faster and has a higher vapor pressure. A liquid with stronger intermolecular forces is more difficult to evaporate and thus has a lower vapor pressure.
At 50°C, ethanoloicacid has the lowest vapor pressure, which is 0.08 atm. Propanone has a vapor pressure of 0.84 atm at 50°C. At 50°C, ethanol has a vapor pressure of 0.30 atm.
Thus, the correct option is 1.
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Answer : Option A) Ethanoic Acid
Explanation : Ethanoic acid has the lowest vapor pressure i.e 0.08 atm at the temperature of 50°C compared to the other given options.
The vapour pressure of propanone at 50°C is 0.84 atm
Ethanol has vapour pressure as 0.30 atm at 50°C
water has vapour pressure of 0.12 atm at 50°C.