A sample taken from a layer of mica In a canyon has 2.10 grams of potassium-40. A test reveals it to be 2.6 billion years old. How much potassium-40 was in the sample originally if the half-life of potassium-40 is 1.3 billion years? A. 4.20 g B. 8.40 g C. 12.6 g D. 16.8 g the E. 25.2 g ​

1. Cl2 + H2O → HOCl + HCl

2. Tooth decay starts when when the pH of the mouth is lower than 5.5. Tooth enamel is made up of calcium phosphate and it is one of the hardest substances of the body. But it is corroded when the pH is less than 5.5. The bacteria of our mouth produce acids by degradation of sugar and food particles remaining in our mouth after eating food.

3. Fluorine salts are added in toothpaste to protect our teeth from tooth decay. Fluorine salts are mildly basic, so they neutrelise the acid in our mouth that leads to tooth decay.

4. Tincture of iodine is iodine, pottasium iodide and sodium iodide dissolved in ethanol. Iodine acts in an antiseptic manner by destroying microbial proteins and DNA.

5. Tincture of iodine is clear and reddish brown liquid.

Answer:

irregular galaxy

pls give brainliest :)

Answer:

irregular galaxy

it is undefined shape

Answer:

I believe it's salt and water

Explanation:

not sure

Answer:

Mixture is a electronic device used to peel the things such as onion ,tomato,ginger, garlic etc.

Answer:

Yes a chemical reaction is taking place.

Explanation:

There is a change in temperature along with bubbling. All signs of a chemical reaction.

Answer:

∆H0 = -222kJ/mol

Explanation:

Using Hess's law, we can find the ΔH of a reaction from the sum of another related reactions as follows:

Using the reactions:

(1) C(s) + O2(g) → CO2(g) ∆H0= -394 KJ/mol

(2) CO(s) + 1/2 O2(g) → CO2(g) ∆H0= -283 KJ/mol

Twice (1):

2C(s) + 2O2(g) → 2CO2(g) ∆H0= 2*-394 KJ/mol = -788kJ/mol

The inverse reaction of (2):

-(2) CO2(g) → CO(g) + 1/2 O2(g) ∆H0= 283 KJ/mol

Twice this reaction:

2*-(2) 2CO2(g) → 2CO(s) + O2(g) ∆H0= 2*283 KJ/mol= 566kJ/mol

Now, the sum of 2*(1) - 2*(2) produce:

2C(s) + 2O2(g) + 2CO2(g)→ 2CO2(g) + 2CO(g) + O2(g) ∆H0= -788kJ/mol +  566kJ/mol

Subtracting the molecules that ar in both sides of the reaction:

2C(s) + O2(g) → 2CO(g) ∆H0 = -222kJ/mol

Answer:

This is because Mendeleev arranged the elements in order of increasing relative atomic mass.

Explanation:

Dmitri Mendeleev is one of the scientists that contributed to the development of periodic table in chemistry. He was able to organise elements into rows according to their atomic mass and into columns based on chemical and physical properties. This is the main reason why his periodic table is still studied even though it has some defects which include:

--> Grouping of elements that are not similar chemically: For example Copper and Silver bear no resemblance with the alkali metals, but they have been placed together in the first group.

--> Position of isotopes: According to his periodic table: Isotopes of an element must be given separate places in the periodic table because they have different atomic masses.

--> Electronic arrangement of elements: It failed to explain the electronic arrangement of elements.

--> Separation of chemically similar elements:

Elements that are chemically similar such as Gold and Platinum have been placed in separate groups.

Answer:

The law of reciprocal proportions states that if two elements react individually with a given weight of a third element, the ratio of the masses with which they combine with the third element are either the same or a simple multiple of the ratio of the masses with which they combine with each other

The compounds formed includes;

1) Nitric oxide, NO

Nitrogen = 46.66% × 30.01 = 14

Oxygen = 53.34% × 30.01 = 16

2) Water, H₂O

Hydrogen = 11.21% × 18.01528 = 2

Oxygen = 88.79% × 18.01528 ≈ 16

3) Ammonia, NH₃

Hydrogen = 17.78% × 17.031 ≈ 3

Nitrogen = 82.22% × 17.031 ≈ 14

The ratio of nitrogen to oxygen in nitric oxide = 14:16 = 7:8

The ratio of nitrogen to hydrogen in ammonia = 14:3

The ratio in which hydrogen and oxygen combine with nitrogen = 3/16

The ratio of hydrogen and oxygen combine with each other in water = 2/16

Therefore, the ratio with which hydrogen and oxygen combine with nitrogen, is (2/3) times the ratio with which they combine with each other, which verifies the law of reciprocal proportions

Explanation:

Answer:

carbon monoxide

I think its correct but I am not sure

Answer: when carbon is heated in air carbon dioxide is formed, so is incomplete combustion which results in carbon monoxide.

Explanation: but when carbon dioxide reacts with more oxygen carbon monoxide is formed i guess.

I AM A BIT SURE BUT HOPE THIS HELPSSSS!!!!

Answer:

1.Physical change

2. Chemical change

3. Heat

4.photosynthesis

5. composition

Answer:

1

Explanation:

Ferric Hydroxide

3. 1

Fe. (OH)

Fe(OH)3

Answer:

iron(III) hydroxide

Explanation:

I just took the quiz!

Answer:

That is a fact.

Explanation:

A therapist can help support you going forward and when in a personal crisis.

A therapist can help us mentally during a personal crisis. This is a fact. because there are personal therapist who helps us to recover from negative thoughts and mental illness.

Individual psychotherapy is the use of psychological techniques to address emotional and personality issues or disorders. In other words, there are treatments that assist in treating emotional disorders in a manner similar to how a doctor would treat a fever or cold.

Milder emotional conflicts to serious psychopathologies might all be a part of these issues. As a result, both those who are depressed and those who are having marital problems can seek counselling.

The problems  that can be healed through psychotherapy include difficulties coping with stressors , trauma and related experiences,   mental illnesses such as depression, anxiety an so on.

Find more on psychotherapy:

https://brainly.com/question/14227208

#SPJ2

Answer:

Arginine is intermediate product formed during the production of urea

The key combination is ornithine, on which the urea molecule is 'created'; intermediates in the procedure contain citrulline and arginine.

The urea cycle is a procedure of conversion of toxic ammonia to negligibly toxic urea. Consequences of the urea cycle are 1 molecule of urea, 2 molecules of ADP, and 1 molecule of both AMP and fumaric acid.

When Ammonia and carbon dioxide recovery During urea decomposition a mixture of gaseous carbon dioxide and also ammonia is accumulated and also immersed into a dilute aqueous urea resolution.

Find more information about Production of Urea here:

https://brainly.com/question/13599932

Answer:

C. Enlargement

Explanation:

Answer:

Mg

Explanation:

Mg forms 2+ ions and mgcl2 has a melting point over 700°C I believe.

Answer:

The scientists should best deal with this measurement by stating that there was an error during measuring and collect further data.

Answer:

C.[tex]3.8\times 10^{-2}[/tex]

Explanation:

We are given that

Initial concentration, [tex][A]_o=4.3 M[/tex]

First half life, [tex]t_{\frac{1}{2}}=56[/tex]minutes

Second half life, [tex]t'_{\frac{1}{2}}=28[/tex]minutes

We have to find K.

The given reaction is zero order reaction.

We know that for zero order reaction

[tex]t_{\frac{1}{2}}=\frac{[A]_o}{2k}[/tex]

Using the formula

[tex]56=\frac{4.3}{2k}[/tex]

[tex]k=\frac{4.3}{2\times 56}[/tex]

[tex]k=3.8\times 10^{-2}[/tex]

Hence, option C is correct.

Zero-order reactions are the reactions when a surface or a catalyst is required for the reaction to proceed and is saturated by the reactant chemicals. The result of the concentration versus the time plot will be a straight line in a zero-order reaction.

[tex]3.8 \times 10 ^{-2}[/tex] is the value of k.

Given,

The given reaction in the question is of zero-order and for that, we know that,

[tex]t \dfrac{1}{2} = \dfrac{[A_{0}] }{2\;\rm k}[/tex]

Substituting the values in the equation we get:

[tex]\begin{aligned}56 &= \dfrac{4.3 }{2\; \rm k}\\\\\rm k &= {4.3 }{2 \times 56}\\\\\rm k &= 3.8 \times 10^{ -2}\end{aligned}[/tex]

Therefore, option C is correct.

Learn more about the zero-order reaction here:

https://brainly.com/question/4638382

Answer:

132.17amu

Explanation:

(14.01+1.01 multiplied by 4)=18.05×2=36.1

36.1+32.07= 68.17

16.00×4=64

68.17+64=132.17

Answer:

132.17 amu

Explanation:

just took the test. got 100

Answer:

Explanation:

Formula

The current = charge / time

The charge is in coulombs

The time has to be in seconds.

1 minute = 60 seconds

2 minutes = 120 seconds.

charge = 180 coulombs

current = 180 / 120

current = 1.5 amperes.

Answer:

Divide the mass of the solute by the total volume of the solution. Write out the equation C = m/V, where m is the mass of the solute and V is the total volume of the solution. Plug in the values you found for the mass and volume, and divide them to find the concentration of your solution.

Here, we have been given that;

Hence, we can note that,

(n) = 32.05

[tex] \\ [/tex]

Thus,

Hence, molarity of the given solution will be 32.05 mg/L.

Answer:

29.41% of Calcium and 47.04% of Oxygen

Explanation:

The percent composition of an atom in a molecule is defined as 100 times the ratio between the mass of the atom and the mass of the molecule.

The mass of the molecule of the problem (Ore) is 46.28g. That means the percent composition of Calcium is:

13.61g / 46.28g * 100 = 29.41% of Calcium

And percent composition of Oxygen is:

21.77g / 46.28g * 100 = 47.04% of Oxygen

Answer:

B. The amount of produd obtained/amount possible * 100

Explanation:

In chemistry, the yield of a chemical reaction is the quantity or amount of products obtained in that chemical reaction. It is calculated by using the following formula:

Percentage yield = Actual yield/theoretical yield × 100

- The actual yield is the amount of products got from a chemical reaction

- The theoretical yield is the amount of product got from using the balanced equation (stoichiometry).

Answer:

its D

Explanation:

Took the test

The specie whose concentration is plotted is D. The rate of reaction is how quickly or slowly hat a reaction proceeds.

The term rate of reaction refers to how quickly or slowly hat a reaction proceeds. A reaction rate plot involves the concentration of the species plotted against time.

Now we can see from the plot that concentration is increasing with time. Since the concentration of products increases with time, then the specie whose concentration is plotted is D.

Learn more about rate of reaction: https://brainly.com/question/11256472

Answer:

yes it does

Explanation:

because the ratios on the reactants and products are equal

The reaction 2Na(s) + Cl₂(g) → 2NaCl(s) obeys the law of conservation of mass.

Yes, this reaction obeys the law of conservation of mass. The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction; it is only rearranged.

In the given reaction, we have 2 sodium atoms (Na) on the left side and 2 sodium atoms (Na) on the right side. Similarly, we have 2 chlorine molecules (Cl₂) on the left side and 2 chlorine atoms (Cl) on the right side. Therefore, the number of atoms of each element is balanced on both sides of the reaction.

Additionally, the total mass of the reactants (2Na + Cl₂) is equal to the total mass of the product (2NaCl). The coefficients in the balanced equation represent the stoichiometric ratios, ensuring that the mass is conserved.

Hence, the reaction 2Na(s) + Cl₂(g) → 2NaCl(s) obeys the law of conservation of mass.

Learn more about law of conservation of mass from the link given below.

https://brainly.com/question/28711001

#SPJ2

Answer:

propene and hydrogen is product

When propanol is heated with concentrated sulphuric acid at 443 K, dehydration takes place and prop-1-ene is formed. In this reaction concentrated sulphuric acid acts as a dehydrating agent.

I. A + HCl gives )-gives 2-chloropropane

II. A --> Combustion ( what product does it form. Write out the equation propene ozonide

III.A ---> Hydrogenation (what product does it form. Write out the equation )propanol