Answer: C) 28.8
Explanation:
Expression for rate law for first order kinetics is given by:
[tex]t=\frac{2.303}{k}\log\frac{a}{a-x}[/tex]
where,
k = rate constant
t = age of sample
a = initial amount of the reactant = 1.000 g
a - x = amount left after decay process = 0.908 g
a) to find rate constant
[tex]4.00yr=\frac{2.303}{k}\log\frac{a}{a-x}[/tex]
[tex]k=\frac{2.303}{4.00}\log\frac{1.000}{0.908}[/tex]
[tex]k=0.024yr^{-1}[/tex]
b) for completion of half life:
Half life is the amount of time taken by a radioactive material to decay to half of its original value.
[tex]t_{\frac{1}{2}}=\frac{0.693}{k}[/tex]
[tex]k=\frac{0.693}{0.024yr^{-1}}=28.8yr[/tex]
The half-life of strontium-90 is 28.8 yr.
What improvements have been made in modern farming? Select all that apply.
1. machines can do more work over less time
2. better seeds sprout and grow much more quickly
3. trains can transport food over long distances faster
4. trains can transport the machines to rural farms once built
5. insecticides used to keep insects off the crops
Answer:
all of them except number 2
Explanation:
Answer:
1,3,4,5 the other perosn is correct
Explanation: That what my quiz said
an _____ bond forms when one element give electrons to another element - one becomes a positive ions and the other a negative ion.
covalent
metallic
ionic
Answer:
ionic
Explanation:
Which is usually associated with a faster reaction rate?
A. diluting a solution of the reactants
B. adding modeling clay to the reactants
C. removing heat energy from the reactants
D. using a solid with a high surface area in the reactants
Answer:
D. using a solid with a high surface area in the reactants, is your correct answer.
Explanation:
Using a solid with a high surface area in the reactants is usually associated with a higher reaction rate.
How are electrons similar and different to the planet Earth?
Answer:
The planets themselves are composed of several trillions or quadrillions or more atoms. As far as hard science is concerned, it would be really hard to picture them as electrons. Conclusion: It can be said with a great accuracy that our planets are NOT huge electrons.
Rutherford's experiments showed that the mass of atoms was mostly concentrated in a very small region, with charge equal to the atomic number- the nucleus. He absolutely did not show, nor is it true, that electrons orbit the nucleus as if they were planets. That was a guess people made in trying to figure out how to picture the atom.
(Hope this helps) Sky
balance the following equation:
!!!!
Answer:
CaC2 + 2H2O > C2H2 + Ca(OH)2
Explanation:
Count the amounts of Ca, C, H, and O, all separately on both sides.
Ca: 1 Ca: 1
C: 2 C:2
H: 2 H: 4
O: 1 O: 2
Now, your goal is to get both sides equal to each other by adding a 2 in front of H2O.
2. Find out the enthalpy change of the CH4 from solid Carbon and Hydrogen gas. C (s)+ 2H2 (g)(CH4(g) (H( = ?
Use the following three equations:
C (s)+ O2 (g)(CO2(g) (H( = -393.5 kJ
H2 (g)+1/2 O2 (g)(H2O(l) (H( = -285.8 kJ
CH4 (g)+ 2O2 (g)( CO2(g)+ 2H2O(l) (H( = -890.3 kJ
Answer:
Approximately [tex]-74.8\; \rm kJ \cdot mol^{-1}[/tex].
Explanation:
Number the three reactions with known enthalpy changes:
[tex]\begin{aligned}& {\rm C\; (s) + O_2\; (g) \to CO_2\; (g)} & \quad \Delta H = -393.5\; \rm kJ\cdot mol^{-1}& \quad (1) \\ & {\rm H_2\; (2) + \frac{1}{2} O_2\; (g) \to H_2O\; (l)} & \quad \Delta H = -285.8\; \rm kJ\cdot mol^{-1} & \quad (2) \\ & {\rm CH_4\; (g) + 2\; O_2\; (g) \to CO_2\; (g) + 2\; H_2O\; (l)} & \quad \Delta H = -890.3\; \rm kJ\cdot mol^{-1} & \quad (3)\end{aligned}[/tex].
The goal is to find a way to combine these three reactions to obtain: [tex]\rm C\; (s) + 2\; H_2\; (g) \to CH_4\; (g)[/tex].
Assume that the three known reactions are combined in this way:
[tex]a \times (1) + b \times (2) + c \times (3)[/tex].
That corresponds to:
[tex]\begin{aligned} & a\; \mathrm{C\; (s)} + \left(a + \frac{1}{2}\, b + c\right) \; \mathrm{O_2\; (g)} + b\; \mathrm{H_2\; (g)} + c\; \mathrm{CH_4\; (g)} \\ & \to (a + c)\; \mathrm{CO_2\; (g)} + (b+ 2\,c )\; \mathrm{H_2O\; (l)}\end{aligned}[/tex].
Compare the coefficients of this reaction with that of the desired reaction:
[tex]\rm C\; (s) + 2\; H_2\; (g) \to CH_4\; (g)[/tex].
Note that some species (e.g., [tex]\rm CH_4\; (g)[/tex]) appeared on the wrong side of the equation. Their desired coefficient should be the opposite of their true coefficient. For example, the coefficient of [tex]\rm CH_4\; (g)[/tex] is supposed to be [tex]1[/tex]. However, because it appeared on the wrong side of the equation, its desired coefficient would be [tex]-1[/tex].
The coefficients of species that are not in the desired equation should be zero.
[tex]\begin{array}{|c|c|c|}\cline{1-3}\text{Species} & \text{Coefficient}& \text{Desired Coefficient} \\ \cline{1-3} \mathrm{C\; (s)}} & a & 1 \\ \cline{1-3} \mathrm{O_2\; (g)} & a + (1/2)\, b + c & 0 \\ \cline{1-3} \mathrm{H_2\; (g)} & b & 2 \\ \cline{1-3}\mathrm{CH_4\; (g)} & c & -1\\ \cline{1-3} \mathrm{CO_2\; (g)} & a + c & 0 \\ \cline{1-3} \mathrm{H_2O\; (l)} & b + 2\, c & 0\\ \cline{1-3}\end{array}[/tex].
Solve for [tex]a[/tex], [tex]b[/tex], and [tex]c[/tex]:
[tex]a = 1[/tex].[tex]b = 2[/tex].[tex]c = -1[/tex]. In other words, the third equation is inverted before being added to the other two equations.In other words, the desired equation is equal to [tex]1 \times (1) + 2 \times (2) - 1 \times (3)[/tex].
By Hess's Law, the enthalpy of the desired equation will be:
[tex]\begin{aligned}& 1\times \Delta H (1) + 2 \times \Delta H (2) - 1\times \Delta H(3) \\ &\approx -393.5 + 2 * (-285.8) - (-890.3) \\ &= -74.8\; \rm kJ \cdot mol^{-1} \end{aligned}[/tex].
's A pitcher contains 1 gallon of
lemonade. All of the lemonade will be
poured into 4 empty glasses. If an equal
amount is poured into each glass, how
much lemonade will be in the first glass?
Answer:
1 quart of lemonade will be in the first cup
Explanation:
1/4th of a gallon is a quart
A gas was held at a constant temperature in a closed system. The initial
pressure of the gas was 1.20 atm, while its initial volume was 2.30 L. The
final volume of the gas was 1.50 L. What was the final pressure of the gas
to the nearest hundredth of an atmosphere?*
Answer:
1.84 atm
Explanation:
P2=V1P1/V2
Temp is irrelevant because it is constant, so all you have to do is rearrange the ideal gas law.
You can check this by knowing P and V at constant T have an inverse relationship and therefore makes this the correct answer.
- Hope that helps! Please let me know if you need further explanation.
Consider a system of four gases. The equilibrium concentration of each product is 2.3 M and the equilibrium concentrations of the reactants are equal. The equilibrium is shown here:
A + B C + D K = 2.6
What is the equilibrium concentration of gas A?
Answer:
The equilibrium concentration of gas A is 1.43 M
Explanation:
Here we have the reaction expressed as follows;
A + B → C + D and
The formula for equilibrium constant is therefore presented as follows;
[tex]K = \frac{[C]\times [D]}{[A]\times [B]}[/tex]
Where:
[C] = [D] = 2.3 M
[A] = [B]
K = 2.6
Hence, we have;
[tex]2.6 = \frac{2.3\times 2.3}{[A]\times [A]} = \frac{5.29}{[A]^2}[/tex]
[tex][A]^2= \frac{5.29}{2.6} = 2.03[/tex]
[A] = 1.43 M
The equilibrium concentration of gas A = 1.43 M.
Answer:
The equilibrium concentration of gas A = 1.43 M
Explanation:
First set up the equilibrium expression:
[tex]K = \frac{[C]\times [D]}{[A]\times [B]}[/tex]
The problem states that each product has a concentration of 2.3M at equilibrium, and that k=2.6
We also know that [A] and [B] are the same.
Since we are solving for [A] I'm going to change [A][B] to A²
[tex]2.6 =\frac{2.3^2}{A^2}[/tex]
Now we just need to solve for A²
A² = 5.29 / 2.6
A² = 2.0346
A = √2.0346
A = 1.43
Therefore, the equilibrium concentration of gas A = 1.43 M.
I need the answers to this question please
The options are
A.0.17g/cm^3
B.5.38g/cm^3
C.0.05g/cm^3
D.8g/cm^3
Answer:
Before submerged 150ml
After submerged: 180ml
rock volume: [tex]180 - 150 = 30[/tex]
formula for density:
[tex] \frac{mass}{volume} = 5.38 [/tex]
[tex] \frac{175}{30} = 5.38 [/tex]
THE ANSWER IS b
prettty sure this is wrong but eh :/ probably correct
Which of the following presents a safety hazard while working in the science laboratory?
A knowing how to use equipment
B wearing safety goggles
C following directions
D working alone
Answer:
D working alone
Explanation:
Working alone is the only option that could potentially be a safety hazard; if you have no one watching your back, errors could occur, like dropping glass or burning your hand, and no one is around to help you.
Choices A, B, and C are not correct because those are all good safety standards.
Calculate the molarity of a KCl solution if 37.3 g of KCl are dissolved in water to give a
final solution volume of 500 ml.
The molarity of a KCl solution if 37.3 g of KCl are dissolved in water to give a final solution volume of 500 ml is 1 M.
What is Molarity?Molarity of a given solution is known as the total number of moles of solute per litre of the solution. A solution that is 1.00 molar (written 1.00 M) contains 1.00 mole of solute for every liter of solution.
Molarity = (No. of moles of solute ÷ Volume of solution in liters)
The unit of molarity is mol L⁻¹.
Molarity is temperature dependent because as temperature changes, volume of the solution also changes.
Given, Mass of KCl = 37.3 g
Molar mass of KCl = 74.5 g/mol
Volume of solution = 500ml = 0.5 L
No. of moles = Mass / Molar mass = 0.5
Molarity = 0.5/0.5 = 1 M
Therefore, The molarity of a KCl solution if 37.3 g of KCl are dissolved in water to give a final solution volume of 500 ml is 1 M.
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Two objects, labeled A and B, are the same size. Object A has a density of 1.21 g/cm3. Object B has a density of 1.37 g/cm3. Both are placed in a beaker of water. Which will float higher in the water?
Answer:
object a will float higher because it has less density.
Explanation:
Answer:
object a will float higher because it has less density.
Explanation:
the radioactive atom 61/27 co emits a beta particle. write an equation showing the decay
Answer:
[tex]\rm _{27}^{60}\text{Co} \longrightarrow \, _{-1}^{0}\text{e} + \, _{28}^{60}\text{Ni}[/tex]
Explanation:
The unbalanced nuclear equation is
[tex]\rm _{27}^{60}\text{Co} \longrightarrow \, _{-1}^{0}\text{e} + \, ?[/tex]
Let's write the question mark as a nuclear symbol.
[tex]\rm _{27}^{60}\text{Co} \longrightarrow \, _{-1}^{0}\text{e} + \, _{Z}^{A}\text{X}[/tex]
The main point to remember in balancing nuclear equations is that the sums of the superscripts and the subscripts must be the same on each side of the equation.
Then
60 = 0 + A, so A = 60 - 0 = 60, and
27 = -1 + Z, so Z = 27 + 1 = 28
Your nuclear equation becomes
[tex]\rm _{27}^{60}\text{Co} \longrightarrow \, _{-1}^{0}\text{e} + \, _{28}^{60}\text{X}[/tex]
Element 28 is nickel, so the balanced nuclear equation is
[tex]\rm _{27}^{60}\text{Co} \longrightarrow \, _{-1}^{0}\text{e} + \, _{28}^{60}\text{Ni}[/tex]
give reason:
Photo chemical decomposition reaction finds application in photography.
Answer:
Photo chemical is caused by the chemical reaction of light. It's initiated by the absorption of energy in the form of light.
Explanation:
When the picture is developed, the thiosulfate dissolved the silver bromide that had been exposed to light more easily than the one that had been kept in the dark,
What causes a molecule to have a net dipole moment?
A. The presence of only nonpolar bonds in the molecule
B. The presence of Van der Waals forces
C. The presence of a net charge that does not cancel out
D. The presence of both covalent and ionic bonds in the molecule
Answer:
Option C
Explanation:
Dipole moment being ac vector quantity has both magnitude and direction. All bonding forces have dipole moment ranging from partially positive to negative moment.
Net dipole moment is the dipole moment arising after summation of all the existing dipole moments. On the basis of dipole moment it is determined whether the molecule is polar or non polar.
Hence, option c is correct
Answer:c
Explanation:
A plastic bag has a volume of 22.3 L at a pressure of 99.5 kPa. If you climb a mountain and the bag expands to a volume of 22.9 L, what is the air pressure at the top of the mountain?
Answer: The air pressure at the top of the mountain is 96.9 kPa
Explanation:
To calculate the new pressure, we use the equation given by Boyle's law. This law states that pressure is directly proportional to the volume of the gas at constant temperature.
The equation given by this law is:
[tex]P_1V_1=P_2V_2[/tex]
where,
[tex]P_1\text{ and }V_1[/tex] are initial pressure and volume.
[tex]P_2\text{ and }V_2[/tex] are final pressure and volume.
We are given:
[tex]P_1=99.5kPa\\V_1=22.3L\\P_2=?\\V_2=22.9L[/tex]
Putting values in above equation, we get:
[tex]99.5\times 22.3L=P_2\times 22.9L\\\\P_2=96.9kPa[/tex]
Thus the air pressure at the top of the mountain is 96.9 kPa
Explain why many Lewis acids and bases are not classified as Arrhenius or Brønsted-Lowry acids and bases
Answer:
Lewis acids cannot have a hydroxide or hydrogen ion or donate a hydrogen ion, so they are neither an Arrhenius or a Brønsted-Lowry acid or base. Lewis bases will always be Brønsted-Lowry bases because they can accept a hydrogen ion.
According to Lewis concept ,Lewis acids cannot have hydroxide or hydrogen ion or donate a hydrogen ion, so they are neither an Arrhenius or a Brønsted-Lowry acid or base. Lewis bases will always be Brønsted-Lowry bases because they can accept a hydrogen ion.
What is Lewis concept?According to Lewis concept, Lewis dot structures are also called as electron dot structures and can be drawn if the molecular formula of a compound is known. It provides information regarding the nature of bond and the position of atoms .
They are also capable of exhibiting the lone pair if any present in a molecule or compound.Lewis defined a base to be an electron pair donor and an acid to be an electron pair acceptor.
They are capable of reflecting electronic structure of elements and even the pairing of electrons . In the diagram, each dot represents an electron while a pair of dots represent a bond between the atoms.
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Write the beta decay equation for the following isotope: 91 38 Sr? Please write out steps
Answer:
[tex]\rm _{38}^{91}Sr \longrightarrow \, _{-1}^{0}e + \, _{39}^{91}Y[/tex]
Explanation:
The unbalanced nuclear equation is
[tex]\rm _{38}^{91}Sr \longrightarrow \, _{-1}^{0}e \, + \, ?[/tex]
Let's write the question mark as a nuclear symbol.
[tex]\rm _{38}^{91}Se} \longrightarrow \, _{-1}^{0}e \, + \, _{Z}^{A}X[/tex]
The main point to remember in balancing nuclear equations is that the sums of the superscripts and the subscripts must be the same on each side of the equation.
Then
98 = 0 + A, so A = 98 - 0 = 98, and
38 = -1 + Z, so Z = 38 + 1 = 39
Then, your nuclear equation becomes
[tex]\rm _{38}^{91}Sr \longrightarrow \, _{-1}^{0}e + \, _{39}^{91}X[/tex]
Element 39 is yttrium, so the balanced nuclear equation is
[tex]\rm _{38}^{91}Sr \longrightarrow \, _{-1}^{0}e + \, _{39}^{91}Y[/tex]
Which of the following units could not be used to measure density?
O A. Kilograms per liter (kg/L)
B. Grams per milliliter (g/mL)
C. Pounds per cubic inch (lb/in)
D. Grams per cubic centimeter (g/cm3)
Answer: Pounds per Cubic inch(lb/in3)
What is the purpose of the part of the male reproductive system that is
highlighted below?
A. Mixes sperm and semen
B. Creates the fluid in semen
C. Manufactures sperm cells
D. Stores sperm cells until they mature
O
Answer:
A
Explanation:
Unlike the female reproductive system, the most parts of the male reproductive system are located outside the body. The mentioned part in the given diagram is urethra and it Mixes sperm and semen. The correct option is A.
What is male Reproductive system?The male reproductive system includes the testes, scrotum, spermatic ducts, male accessory glands and phallus. All these organs work together to produce sperms, the male gamete, male sex hormones and other components of semen.
The phallus and urethra are the parts of both the reproductive and urinary systems. Scrotum, seminal vesicles, vas deferens, testicles and prostate constitute all the remaining male reproductive system.
The urethra is a tube like structure which is the region included in the urinary tract that takes the urine from the bladder where the semen is ejaculated.
Thus the correct option is A.
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I need an answer ASAP!!
Answer:
C:
Explanation:
Current flows from negative to positive.So the electrons will be moving left.
when a current is applied, positive charged copper ions (called cations) leave the anode (positive electrode) and move to the cathode (negative electrode).
Why is wind named from where the wind is blowing from?
Winds are always named from the direction it blows from
Uneven heating of Earth's surface,in turn,causes differences in air pressure at various locations. Heated air rises,creating an area of low pressure beneath. Cooler air descends, creating an area of high pressure
High levels of carbon dioxide in the blood trigger which of the following responses in the body?
Select one:
a decrease in the production of sweat
a decrease in the speed of the pulse
an increase in the rate of breathing
an increase in the rate of digestion
The amplitude of a wave is the vertical distance from the midpoint to either the crest or the
trough of the wave
True
False
what is an example of a strong base?
HCl
NaCl
NaOH
HF
Answer:
The answer is NaOH
Explanation:
Strong bases are characterized by the fact that they dissociate completely in an aqueous solution. In this case, sodium hydroxide, NaOH, is classified as a strong base because it dissociates completely in an aqueous solution to form sodium cations, Na+, and hydroxide anions, OH−. Also, it is strong because it totally breaks in its ion. And the base which breaks totally in its atom called the strong base and which doesn't it that is a weak base.
Answer:
NaOH
Explanation:
Got it right in the test. Please mark as brainliest
What Le Chatelier’s factors cause an increase in the concentration of Hb(CO)4(aq) in the Hb(CO)4(aq) + 4O2(g)Hb(O2)4(aq) + 4CO(g)
Answer:
Explanation:
Hb(CO)4(aq) + 4O2(g) ⇄ Hb(O2)4(aq) + 4CO(g)
1 ) If we increase the concentration of CO(g) , the reaction above will proceed in reverse direction to decrease its concentration, according to Le Chatelier principle. Hence more of Hb(CO)4(aq) will be formed.
2 ) If we decrease the concentration of O₂ , then also , reaction will proceed in reverse direction . Hence concentration of Hb(CO)4(aq) will be increased .
What is the molarity of a solution in which 0.45 grams of sodium nitrate (NaNO3) are dissolved in 265mL of the solution?
A. 29.8M
B. 87.2M
C. 0.02M
D. 0.52M
Answer:
M=0.02
Explanation:
85 g NaNO3 -> 1 mol NaNO3
0.45 g NaNO3 ->x
x=(0.45 g NaNO3 * 1 mol NaNO3)/85 g NaNO3 x= 5.3 x 10^-3 mol
265 mL= 0.265 L
M= mol solute/ L solution
M= 5.3 x 10^-3 mol NaNO3/0.265 L M=0.02
A weather forecast shows 35 m/h on the weather map. Which weather component does this number represent?
A.Humidity
B. Precipitation
C.Wind direction
D.Wind speed
Answer:
D. Wind Speed
Explanation:
When the question brings up 35 m/h, the m/h stands for Miles per Hour. What option can you measure the miles per hour. Here's a hint, it applies to cars as well when cops give your parents speeding tickets. Miles per Hour = Speed. So, you are measuring the wind speed.
An ideal gas, such as helium, is in a sealed container made of hard steel. If the container is heated, what would happen to the gas trapped inside the container?
Group of answer choices
The volume of the gas will decrease
The pressure of the gas will increase
The volume of the gas will increase
The pressure of the gas will decrease
Answer:
The correct answer is The pressure of the gas will increase
The volume of the gas will increase
Explanation:
Step 1: Data given
The gas in a container is heated, this means the temperature increases
Suppose we start with a temperature of 100 K and a pressure of 1 atm and a volume of 1L
Step 2:
V1/T1= V2/T2
⇒V1 = the initial volume = 1L
⇒T1 = the initial temperature = 100 K
⇒V2 = the new volume = TO BE DETERMINED
⇒T2 = the increased temperature = 200 K
1/100 = V2 / 200
V2 = 2 L
This means when the temperature increases, the volume will increase
P1/T1 = P2/T2
⇒P1 = the initial pressure = 1 atm
⇒T1 = the initial temperature = 100 K
⇒P2 = the new pressure = TO BE DETERMINED
⇒T2 = the increased temperature = 200 K
1/100 = P2 / 200
P2 = 2 atm
This means when the temperature increases, the pressure will increase
The correct answer is The pressure of the gas will increase
The volume of the gas will increase
