CHEMISTRY HIGH SCHOOL

After 32 days, 5 milligrams of an 80-milligram sample of a radioactive isotope remains unchanged. What is the half-life of this element?(1) 8 days (3) 16 days
(2) 2 days (4) 4 days

Answers

Answer 1
Answer:

Unstable heavy atoms will undergo radioactive decay to produce stable species. The half life time of the isotope which undergone a decay of 75 mg in 32 days is 18 days.

What is half life time?

The half life time of a radioactive sample is the time taken to reduce it to half of the initial amount by decay.

The heavy unstable material have very short half life and they will easily undergoes radioactive decay by emitting certain radiation.

Radioactive decay is a firs order reaction and have the equation to find the radioactive constant as follows:

\lambda = (1)/(t) log([Ni])/([Nt])

Where, t is the time of decay and Ni and Nt be the initial and final amount respectively.

It is given that 5 mg is remaining out of 80 mg after 32 days. Thus the radioactive constant is calculated as follows:

\lambda = (1)/(32 days ) log (80)/(5) \n \n = 0.0376. days ^(-1)

Now the half life time of the decay is calculated as below:

t(1/2) = 0.693 /decay constant

      = 0.693/0.0376

      = 18 days

Therefore, the half life time of the isotope which undergone a decay of 75 mg in 32 days is 18 days.

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Answer 2
Answer: m=m_0 * ((1)/(2))^(t)/(t_(1/2))
m - the mass that remains unchanged, m₀ - the inital mass, t - the time of decay, t1⁄2 - the half-life

t=32 \ days \n m=5 \ mg \n m_0 = 80 \ mg \n \n 5 = 80 * ((1)/(2))^(32)/(t_(1/2)) \ \ \ \ \ \ \ |/ 80 \n (5)/(80)= ((1)/(2))^(32)/(t_(1/2)) \n (1)/(16)=((1)/(2))^(32)/(t_(1/2)) \n ((1)/(2))^4=((1)/(2))^(32)/(t_(1/2)) \n 4=(32)/(t_(1/2)) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ |* t_(1/2) \n 4t_(1/2)=32 \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ |/ 4 \n t_(1/2)=8

The half-life is (1) 8 days.

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The clown fish hides inside the poisonous tentacles of the sea anemone. Since most other fish are unable to survive the anemone’s stings, the clown fish is protected from predators. In addition, it can feed on the leftovers from the anemone’s meals. This symbiotic relationship is called _____________________.A.
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B.
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Answers

Answer: C: commensalism   please give me hearts and stars because the answer is right!!

Explanation:

The relationship between the clown fish and the deadly sea anemone can be classified as commensalism. Though the sea anemone’s tentacles are covered with thousands of nematocysts (tiny, venomous harpoons), the clown fish is protected by a thick coat of mucus and is not harmed by the anemone’s venom. The clown fish is therefore protected from predators and is also able to get leftover food from the anemone's meals. Since the clown fish ultimately benefits from this arrangement and the sea anemone neither benefits nor suffers because of the clown fish, the relationship is commensalistic.

Final answer:

The clown fish and the sea anemone exhibit a mutualistic relationship, where both organisms benefit. However, among the options provided in the question, the most accurate is 'symbiosis', which broadly denotes a close, long-term interaction between different biological species.

Explanation:

The symbiotic relationship between the clown fish and the sea anemone is referred to as mutualism. This term, which is missing from the options, indicates a relationship in which both organisms benefit. The clown fish is protected from predators and has access to food remnants, whereas the sea anemone gets cleaned by the clown fish, which removes parasites and debris. Among the options provided, the closest would be symbiosis (option D), as it describes a close, long-term interaction between different biological species, which can include mutualism, commensalism, and parasitism.

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The metalloid that has three valence electrons is?

Answers

The metalloid that has three valence electrons is Boron~

Answer:

The metalloid that has three valence electrons is Boron~

Explanation:

Water has a higher boiling point than expected because A. there is so much water vapor in the atmosphere. B. water molecules are not very massive. C. hydrogen and oxygen form single covalent bonds. D. of the strong attractions between polar water molecules

Answers

The correct answer is C. Water has a higher boiling point than expected because hydrogen and oxygen form single covalent bonds. Molecules of water is bound together by strong attractions which needs high energy to break resulting to a higher boiling point of water than most substances.

Final answer:

Water has a higher boiling point than expected because D. of the strong attraction between polar water molecules.

Explanation:

The higher boiling point of water is due to the strong attraction between polar water molecules. Water molecules are polar because of the unequal distribution of electron density between the oxygen and hydrogen atoms, resulting in a slightly positive charge on the hydrogen atoms and a slightly negative charge on the oxygen atom.

Thus, these partial charges create attractive forces called hydrogen bonds between neighboring water molecules, making it difficult to separate the molecules and requiring more heat energy to overcome these attractive forces and reach the boiling point.

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A particle that orbits the nucleus in an atom is called an

Answers

Good Morning

Answer : A particle that orbits the nucleus in an atom is called an Electron


Hint : Electron, negatively charged particle orbiting the nucleus. Same number as protons in neutral atoms


I hope that's help !


Happy Sunday :)
This would be a proton.It has a positive charge and is found in the nucleus. Don't get it confused with an electron this is not inside the nucleus but floats around the nucleus.

Determine which elements or compounds are products in the follow reaction equation: calcium + chlorine → calcium chloride A. calcium, chlorine, and calcium chloride B. calcium C. calcium and chlorine D. calcium chloride Reset Selection

Answers

Answer: D. calcium chloride

Explanation:

In reaction equations, reactants are on the left side of the arrow and products are on the right side of the arrow. So, our reactants are the elements calcium and chlorine, and our product is the compound calcium chloride.

I hope this helps! :)

Final answer:

In the given chemical reaction equation, the product is calcium chloride as it is formed from the reaction of calcium and chlorine.

Explanation:

In a chemical reaction, substances that are formed as a result of the reaction are known as products. In the given chemical equation, calcium (Ca) reacts with chlorine (Cl2) to produce calcium chloride (CaCl2). Therefore, in this reaction equation, the product is calcium chloride. The reactants, substances that exist before the reaction, are calcium and chlorine. So, the correct answer to your question is D. calcium chloride.

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Over 100 existing elements are listed and classified on the ____________________.

Answers

Final answer:

The Periodic Table of Elements lists over 100 known elements, providing critical information such as the element's atomic number, symbol, name, and atomic mass. Elements are grouped based on their chemical properties and electron configuration.

Explanation:

Over 100 existing elements are systematically organized and displayed on the Periodic Table of Elements. Each box on the Periodic Table represents a different element and provides critical information such as the element's atomic number, symbol, name, and atomic mass. Elements are grouped together based on their chemical properties and electron configuration, which is a representation of the organization of electrons around the nucleus.

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Final answer:

Over a hundred elements, both naturally occurring and experimentally discovered, are listed and classified on the Periodic Table of the Elements. They are sorted by atomic number, and those with similar properties and valence shells are grouped into columns and rows respectively.

Explanation:

Over 100 existing elements are listed and classified on the Periodic Table of the Elements. This list of elements is arranged in ascending order of atomic number, which is the number of protons in each nucleus. The periodic table not only identifies the chemical symbol, atomic number, and mass number of each element but also groups elements according to their propensity to react with other elements.

It's important to note that elements found on the periodic table have an equal number of protons and electrons. However, the number of protons and neutrons may not always be equal across all elements. In addition to the 92 naturally occurring elements, there are several larger, unstable elements that have been discovered experimentally

Aside from organizing elements according to their atomic number, the periodic table is also structured in a way that elements with similar properties compose columns in the table, while elements with the same number of valence shells compose rows, making it an essential tool for understanding and predicting chemical behaviors.

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