The half-life of uranium-235 is 700 million years. If there are 2000 g of uranium-235 in the original sample, what happens after 2100 million years have passed? Select all that apply.
A.
One half-life has passed.
B.
500 g of the original sample remains.
C.
Two half-lives have passed.
D.
250 g of the original sample remains.
E.
125 g of the original sample remains.
F.
Three half-lives have passed.
Answer:
The correct answer is - D. 250 g of the original sample remains. and F. Three half-lives have passed.
Explanation:
The half-life is the time is required for a quantity to reduce to half of its initial value. In this given case,
The half life cycle - 700 million years
The number of half-life cycle after 21 million years - 21/7
= 3 half life cycles.
Initial amount = 2000 g
after one half-life or 700 million years - 2000/2 = 1000 g
second half-life or 1400 million = 1000/2 = 500 g
third or 2100 million years ago = 500/2 = 250 g.
t-Butyl alcohol was produced by the liquid-phase hydration (using water, W) of isobutene (I) over an Amberlyst-15 catalyst.
a. True
b. False
Answer:
True
Explanation:
This is because, The hydroboration oxidation of an alkene which is isobutene in the presence of a catalyst will result to alcohol as the product . Therefore, the OH group will attach or link itself to the carbon which is less obstructed. Thus this reaction is in accordance to Anti-Markownikoff's rule.
So isobutene on hydroboration oxidation will produce ter isobutyl alcohol.
a. Explain why the pie pans flew off the van de Graaf generator
b. Give a detailed explanation of why the rabbit fur and the plastic rod were attracted to each other after we rubbed them together but not before
c. Describe two things you could change to increase the force of electrical attraction between two objects (this is about Coluomb's Law).
Answer:
Static energy is an energy between two charges.
Explanation:
a). A van de Graff generator builds up a positive electric charge on the dome by separating the negative static electric charges from the positive static charge using a quickly moving belt. The positive charge collects on the large metal dome of the generator. When the charge builds up is large enough, a lighting like spark can shoot from the dome to a grounded discharge rod.
Like electric charges always repel each other, and oppositely electric charges will attract each other. When the aluminum pans are being charged by the van de Graff generator, then each of them attain the same positive polarity similar with the dome. Thus, positive charge starts to accumulate over the surface of each of the pie pan. Each aluminum pan repels the others. These repulsive forces between the pans are so strong that they succeed in overcoming the gravity force and thus the top of the pan is pushed away from the generator's dome.
b). Static electricity is produced by a concentration of negative and positive electric charges. Like charges pushes away each other while unlike charges pulls each other.
Objects generally have same numbers of positive charges as well as negative charges. And if there is any small imbalance in numbers of the charges on the object, it is charged.
Negative charges easily torn away from the materials like the fur or hair. Also, the negative charges are held on other materials like the plastics. If we rub a plastic rod with fur, the negative charges will get transferred from fur to rod. The rod gets negatively charged and the fur is positively charged. As a result, the rabbit fur and the plastic rod were attracted to each other.
c). Coulomb's law stated that :
[tex]$F=\frac{KQ_1Q_2}{d^2}$[/tex] .............(i)
where, [tex]$Q_1$[/tex] and [tex]$Q_2$[/tex] are the charges of two objects d is the distance between two objects.
As from the above equation, we can say that force of electrical attraction between two objects depends on the charges and the distance between objects.
1. The electrical force between two charged object is inversely proportional to the distance of separation between two objects.
Decreasing separation distance (d) between the objects will increase its attraction force.
2. And, increasing the charges of two objects(+ve and -ve) increases the force of attraction between two objects.
A scientist observes the cells of a newly discovered animal under a
microscope. Which of the following cell parts is the scientist likely to find?
A. Cell membrane, chloroplasts, and a nucleus
B. Cell wall, cell membrane, and ribosomes
O C. Cell wall, chloroplasts, and lysosomes
D. Cell membrane, ribosomes, and a nucleus
Answer:
D
Explanation:
The rest have characteristics of a plant cell
(a) Define the following terms
(i) Periodic Table
(ii) Period on the Periodic-table
(iii)Colum on the Periodic-Table
Explanation:
i.Periodic table:It is a chart or table of the elements arranged into columns and rows according to their physical and chemical properties.
ii.Period on the periodic table:The horizontal rows of elements
iii.Column on the periodic table:The vertical representation of elements
To calculate the freezing point of an ideal dilute solution of a single, nondissociating solute of a solvent, the minimum information one must know is: a. the same quantities as in B, plus the freezing point of the pure solvent b. the molality (of the solute) and the freezing point depression constant of the solvent c. all of the quantities in C, plus the weight of the solvent d. all of the quantities in C, plus the molecular weight of the solute e. the molality (of the solute)
Answer:
the same quantities as in B, plus the freezing point of the pure solvent
Explanation:
Using the formula;
∆T = K· m. i
Where;
∆T = freezing point depression of the solution
K = freezing point depression constant
m = molality of the solution
i = vant Hoff factor
Since the solute is a single, non-dissociating solute, i=1
The equation reduces to;
∆T = K· m
So we must know the freezing point depression constant and the molality of the solution.
In addition; ∆T = freezing point of pure solvent- freezing point of solution
Hence, if we use the formula, ∆T = K· m to calculate ∆T, then we must also know the value of the freezing point of pure solvent in order to compute the freezing point of the solution.
9. A student is dissolving sugar in water. What can
the student do to make the sugar dissolve faster?
A. Nothing, sugar will not dissolve in water
B. Add more water.
C. Add ice to the water.
D. Stir the solution.
Answer:
D
Explanation:
Sugar will dissolve faster when you stir the solution quickly because the act of stirring increases kinetic energy which increases the temperature.
what element in magma is most abundant
Answer:
Oxygen and Silicon
Explanation:
Oxygen and Silicon are the most abundant elements in magma, SiO₂
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It took Mrs. Murphy 5.5 hours traveling at a rate of 113 km/hr to finally reach her parents house.
How far did she travel?
Developments in agricultural since the 1960s that have made it easier to grow food are known as the
Answer:
The correct answer is - the green revolution.
Explanation:
The green revolution that helps in the developments in agriculture since the 1960s increase great production in growing food grains and crops by introducing and using natural fertilizers, pesticides, high-yielding varieties, and management tools and techniques. It also includes the engineering machines application in agriculture.
The developing varieties of grains and crops with high resistance to disease and pests, weedicides, and many more provided a great leap in avoiding or reducing agricultural losses.
A 1.00 x 10^-10 M solution of chloric acid Please help me solve this to find pH and pOH
Answer: The pH of solution is 10.
The pOH of the solution is 4.
Explanation:
pH is the negative logarithm of concentration of hydrogen ion.
As given concentration of acidic solution is [tex]1.00 \times 10^{-10} M[/tex]. Therefore, pH of the solution is calculated as follows.
[tex]pH = -log [H^{+}]\\= -log (1.00 \times 10^{-10})\\= 10[/tex]
The relation between pH and pOH is as follows.
pH + pOH = 14
pOH = 14 - pH
= 14 - 10
= 4
Thus, we an conclude that pH of solution is 10 and pOH of the solution is 4.
In the graph above, what is the relationship between volume and temperature? Does this data support Charles' Law?
Hint: is it a direct or inverse relationship? How does volume change with temperature changes?
Answer:
No the graph does not support Charles' Law. Both volume and temperature increase so it would be a direct relationship.
Explanation:
24. When is the energy released in a reaction?
Answer:
exothermic
Explanation:
because it releases energy
A chemist weighs out 0.138 grams of a unknown diprotic acid into a 222 volumetric flask and makes a 222 ml solution of it with distilled water. They titrate this solution with 0.1800 M Magnesium hydroxide. When the titration reached the equivalence point, the chemist found that they had added 22.8 mL of magnesium hydroxide. Calculate the molar mass of the unknown acid.
Answer:
33.6g/mol is the molar mass of the unknown acid
Explanation:
The molar mass of a substance is defined as the ratio of the mass of the acid (0.138g) and the moles of the substance.
The diprotic acid, H₂X, reacts with magnesium hydroxide, Mg(OH)₂ as follows:
H₂X + Mg(OH)₂ → MgX + 2H₂O
Where 1 mole of the diprotic acid reacts per mole of magnesium hydroxide
To find the moles of the acid and solve the molar mass of it we need to find the moles of magnesium hydroxide added to the solution at equivalence point = Moles of diprotic acid as follows:
22.8mL = 0.0228L * (0.1800moles / L) = 4.104x10⁻³ moles of the acid.
The molar mass is:
0.138g / 4.104x10⁻³ moles =
33.6g/mol is the molar mass of the unknown acidHow many hydrogen molecules are in h2
Answer:
two
Explanation:
The symbol “H” means the hydrogen atom; “2H” means two hydrogen atoms that do not make a molecule: they are just two separate (individual) atoms; “H2” means the hydrogen molecule (two hydrogen atoms that came together, sharing their electrons); “2H2” means two separate hydrogen molecules.
When 15. 3 g NaCl reacts with 81.70 g Pb(NO3)2, sodium chloride is the limiting reactant, according to the balanced equation below. How many grams of lead (II) nitrate will remain after the reaction stops?
2 NaCl + 1 Pb(NO3)2 → 2 NaNO3 + 1 PbCl2
Answer:
[tex]m_{Pb(NO_3)_2}^{leftover}=38.34g[/tex]
Explanation:
Hello there!
In this case, given the chemical reaction by which the sodium chloride reacts with lead (II) nitrate and the former is the limiting reactant, it is possible to calculate the mass of lead (II) nitrate that are actually consumed according to the 2:1 mole ratio between them:
[tex]m_{Pb(NO_3)_2}=15.3gNaCl*\frac{1molNaCl}{58.44gNaCl}*\frac{1molPb(NO_3)_2}{2molNaCl} *\frac{331.21gPb(NO_3)_2}{1molPb(NO_3)_2} \\\\m_{Pb(NO_3)_2}=43.36gPb(NO_3)_2[/tex]
Thus, the leftover of lead (II) nitrate is:
[tex]m_{Pb(NO_3)_2}^{leftover}=81.70g-43.36g\\\\m_{Pb(NO_3)_2}^{leftover}=38.34g[/tex]
Best regards!
what is scienceand technogy
Answer:
Science and technology is an interdisciplinary topic encompassing science, technology, and their interactions: Science is a systematic enterprise that builds and organizes knowledge in the form of explanations and predictions about nature and the universe.
Explanation:
which statement is not a postulate of the kinetic molecular theory g the volume of the gas molecules is comparable to the volume of the container?
Answer:
The pressure and volume of a gas are inversely related
Explanation:
If we look at all the options stated; we will notice that all the statements are correct according to the kinetic theory of gases; except the statement "The pressure and volume of a gas are inversely related".
Recall that the inverse relationship between pressure and volume of a gas is captured by Boyle's law and not the kinetic molecular theory. Hence this statement is not part of the kinetic molecular theory.
Are sperm and egg cells exact copies of the plant cell
Answer:
No
Explanation:
thats scientifically impossible
What mass of oxygen is needed to react with 11.60 g of iron?
Answer:
6.29oc
Explanation:
Select all the correct answers.
Which statements demonstrate scientific research bias?
Jennifer studied the most convenient sample instead of obtaining a sample that better represented the entire population.
Tyler's conclusion was supported by his data, but it did not agree with his hypothesis.
Manny was presented with several possible research topics, and he chose the one he found most interesting.
Ellie carried out the same experiment four times, and she obtained the same result every time.
Brad expected a certain result from his experiment, so he interpreted his data in a way consistent with that result.
Answer:
1. Jennifer
Jennifer tried to cut corners and exclude a chunk of people from the population, making her results biased.
2. Brad
Brad was just seeing what he wanted to see, instead of facing the results of his experiment, which makes him scientifically biased. It's known as 'cherry-picking' informally.
Explanation:
Why are the rest not biased?
1. Tyler
You don't need your results and conclusion to agree with your hypothesis. A hypothesis is just your guess, it's not absolute and doesn't demonstrate bias if it doesn't agree with your conclusion.
2. Manny
He simply chose a topic he was interested in. It would be a different story if he already had a topic, but only chose information that agreed with his hypothesis, neglecting other pieces of information.
3. Ellie
This demonstrates no bias. She carried out an experiment and, according to experimental data, received the same results every time. She did not purposefully alter them to make them what she wanted to see.
Answer:
1. Jennifer
Jennifer tried to cut corners and exclude a chunk of people from the population, making her results biased.
2. Brad
Brad was just seeing what he wanted to see, instead of facing the results of his experiment, which makes him scientifically biased. It's known as 'cherry-picking' informally.
Explanation:
The surface forces that change the surface of the earth are:
Faulting
Erosion
Volcanoes
Earthquakes
Glaciers
Living things
Weathering
Folding
Help ASAP!!
Answer:
erosion
glacier
living things
weathering
Explanation:
What's you're favorite year?
Answer:
2020 cause of the lockdown
Explanation:
What will change more solid NiCl2 is added
Why is a sandy shore hot on a summer day?
A. The sand is heated through thermal conduction,
B. The sand is chemically heated.
C. The sand is heated through radiation.
D. The sand is heated through convection.
Answer:
C. the sand is heated through radiation
Explanation:
The Haber process generates ammonia from nitrogen and
hydrogen gas through the following chemical equation.
N2 + 3H2 + 2NH3
Which is the excess reagent in the Haber reaction if equal
moles of Hydrogen and Nitrogen are used?
The Haber process generates ammonia from nitrogen and hydrogen gas, and nitrogen gas is the excess reagent.
What is stoichiometry?Stoichiometry of reaction tells about the relative amount of reactants and products after and before the chemical reaction.
Given chemical reaction is:
N₂ + 3H₂ → 2NH₃
From the stoichiometry of the reaction it is given that:
1 mole of N₂ = produce 2 moles of NH₃
3 moles of H₂ = produce 2 moles of NH₃
1 moles of H₂ = produce 2/3=0.66 moles of NH₃
So, nitrogen is present in the excess quantity.
Hence, nitrogen gas is the excess reagent.
To know more about stoichiometry, visit the below link":
https://brainly.com/question/16060199
Answer:
Its N2
Explanation:
yea lol
BTw this is for Ck-12
Please help me on 6 and 8 thanks
Answer:
6.) 3, 12, 1, and 4 8.) 4, 1, and 3
Explanation:
By multiplying subscripts inside and outside of the parentheses you can count the number of atoms that are present. I recently answered a question for you and I did the math wrong I am going to go back and comment so you know which one and I will correct my errors. Sorry for the inconvenience!
the number of atoms in number 6:
N: 3
H: 12
P: 1
O: 4
the number of atoms for number 8:
Ca: 4
C: 1
O: 3
hope I clarified my mistake and helped you! :)
What type of bonds are formed in N2O4?
Answer:
Non- polar and Covalent bonds
Match each definition to the appropriate term.
1. The extent of randomness in a system _______________
2. Difference of the enthalpy (of a system) minus the product of the entropy and absolute temperature ____________
3. Solution in which no more solute can be dissolved in the solvent _____________
4. Sum of the internal energy plus the product of the pressure and volume for a reaction _____________
5. The condition that a reaction takes place without outside help ____________
a. Spontaneity
b. Saturated solution
c. Entropy
d. Enthalpy
Answer:
The definition of the terms are:
1.) The extent of randomness in a system ENTROPY.
2.) Difference of the enthalpy (of a system) minus the product of the entropy and absolute temperature is GIBBS FREE ENERGY.
3.) Solution in which no more solute can be dissolved in the solvent SATURATED SOLUTION.
4.)Sum of the internal energy plus the product of the pressure and volume for a reaction ENTHALPY.
5.) The condition that a reaction takes place without outside help SPONTANEITY.
Explanation:
ENTROPY is defined as the degree of disorderliness(randomness) of a system. It is usually denoted by 'S'. Entropy change is a factor that contributes to the driving force behind Chemical reactions. In a system, the greater the degree of disorderliness the higher the entropy and the greater the tendency for the reaction to take place. Therefore the extent of randomness in a system is ENTROPY.
GIBBS FREE ENERGY is defined as the difference of the enthalpy (of a system) minus the product of the entropy and absolute temperature. Both the enthalpy (H) and entropy (S) can determine how a chemical reaction will occur.A scientist J. Willard Gibbs related the two by introducing a third parameter called the FREE ENERGY. This is usually represented as (G). Mathematically,
∆ G = ∆H - T∆S
Where T is the absolute temperature of the system.
When ∆G is negative the reaction is feasible, that is, it will occur. When ∆G is positive the reaction is not likely to occur. When it is zero the reaction is at equilibrium.
SATURATED SOLUTION is defined as a solution in which no more solute can be dissolved in the solvent. This means that it's a solution that contains as much solute as it can dissolve at that temperature in the presence of undissolved solute particles. In a saturated solution, the dissolved solutes and undissolved solutes are in equilibrium at that temperature. Any change in temperature will disturb this equilibrium and the system must alter to counter the change.
ENTHALPY is defined as the Sum of the internal energy (E) plus the product of the pressure(P) and volume(V) for a reaction. This is usually represented with the symbol 'H'. Mathematically,
H = E + PV.
The rate of chemical reaction depends on the frequency of effective collision between the reacting particles. When this occurs,the colliding particles becomes activated with increased kinetic energy. This energy must exceed a particular energy barrier called activation energy ( an internal energy) before a reaction can take place while the heat of the reaction is called ENTHALPY (H).
SPONTANEITY is the condition that a reaction takes place without outside help. This reaction doesn't require any energy input because the products at a more stable lower energy state than the reactants.
What refers to the attractive forces that exist between molecules?