Answer:
3.5 milligram
Explanation:
From;
N/No = (1/2)^t/t1/2
Where;
N = amount of Po-210 that remains unchanged after 414 days
No = 28.0 milligram of Po-210 originally present
t = 414 days
t1/2 = half life of Po-210 = 138 days
Substituting values;
N/28 = (1/2)^414/138
N/28 = (1/2)^3
N/28 = 1/8
8N = 28
N = 28/8
N = 3.5 milligram
Oil and water placed in a jar will separate. Even when shaken and mixed, the oil still separates from the water.
Which best describes oil and water?
Oil and water are highly soluble because they have separate chemical properties.
Oil and water have a low solubility because they have separate chemical properties.
Oil and water are highly soluble because they exert different pressures.
Oil and water have a low solubility because they exert different pressures.
Answer:
Probably B?
Explanation:
I don't have one...
Hope it helps I guess..
Answer: i think is B
Explanation: HATE ME IF IM WRONG
If a cake recipe requires 25g of sugar, how much sugar will the baked cake contain
what is the boiling point of carbon?
Answer: 3915 K (3642 °C, 6588 °F)
Answer:
8,721°F
OR
4,827°C.
Explanation:
Good Luck!
A student mixes two chemicals in a test tube. She notices that the mixture starts to bubble and the test
tube feels very warm. The student most likely concludes that the mixture is-
F. a chemical reaction that happened too quickly.
G. an endothermic reaction that absorbed thermal energy.
H. an exothermic reaction that released thermal energy.
J. not a chemical reaction.
Answer:
H. an exothermic reaction that released thermal energy.
Explanation:
The student will most conclude that this is a chemical reaction in which thermal energy is released to the environment.
Such reactions accompanied by the release of thermal energy are exothermic reactions.
In an exothermic change, heat is liberated to the surrounding. The surrounding becomes hotter at the end of the changes. For such reaction we say that enthalpy change is negative.For endothermic reactions, heat is absorbed. At the end of the reaction, the system is cold.
Consider the reaction: 2AB2 → A2 + 2B2 You start with one mole of AB2 and the reaction is done at constant pressure of 3.7 atm and 28.2 °C. Assume all gases behave like ideal gases. What is the value of the work (in J)?
Answer:
-2503.2J
Explanation:
At constant pressure, change in work follows the equation:
W = -P*ΔV
Where W is work, P is pressure (3.7atm) and ΔV is change in volume
We can obtain change in volume using ideal gas low:
ΔV = ΔnRT/P
Where Δn is change in moles (3moles of products - 2 moles of reactants = 1)
R is gas constant (0.082atmL/molK)
T is absolute temperature (28.2°C + 273.15 = 301.35K)
P is pressure (3.7atm)
ΔV = ΔnRT/P
ΔV = 1mol*0.082atmL/molK*301.35K/3.7atm
ΔV = 6.69L
And work is:
W = -3.7atm*6.69L
W = -24.71atmL
1atmL = 101.3J
-24.71atmL * (101.3J / 1atmL) =
-2503.2J
For questions 14-16 pick out the variables that will be needed to answer the following question: Do trees grow faster if it is wetter in the summer?
14) What is the independent variable?
a.) amount of rain
b.) no rainfall
c.) amount of growth
15) What is the dependent variable?
a.) amount of rain
b.) no rainfall
c.) amount of growth
16) What is the control?
a.) amount of rain
b.) no rainfall
c.) amount of growth
Answer:
14) A. amount of rain
15) C. amount of growth
16) B. no rainfall
Explanation:
6e7eyehdjjdueebbevdvdvebe
Please select the word from the list that best fits the definition left standing after the collapse of a sea arch
Answer:
Sea Stack
Explanation: :)
Answer:
A
Explanation:
What signs of a chemical reaction did you observe during the lab? Check all that apply.
color change
temperature change
mass change
formation of a gas
formation of a solid
formation of a liquid
Answer:
1, 4, 5
Explanation:
1 - Color Change
4 - Formation of Gas
5 - Formation of Solid
(correct on ed)
Answer: A, D , E
Explanation:
In a water molecule (H2O), the oxygen atom has two unshared pairs of electrons and two bonding pairs of electrons. How do the unshared pairs affect the bond angle?
Answer:
They reduce the bond angle to be slightly lower than the tetrahedral bond angle, approximately 104.45 degrees.
Explanation:
The unshared pair of electrons or lone pair electrons in order to have the minimum repulsion possible with each other pushes the other bonding pairs closer together making the bond angle smaller or bent.
The bond angle is slightly lower than the tetrahedral bond angle of 108 degrees, leaving the water molecule with a bent molecular geometry.
QUICK
Which of these is a ball and stick model?
Does the following equation follow the law of conservation of mass? Show your work
AgNO3 → Ag2 + NO3
Answer:
No.
Explanation:
If the equation follows the law of conservation of mass, then the amount of reactants must be equal to the amount of products. That is not the case for the provided equation due to 1 Ag on the reactants side versus 2 Ag on the products side.
Which statement best describes what would happen to an ecosystem once the sun is removed?
A. The functions within the ecosystem will eventually stop & everything will die off.
B. The ecosystem will continue to thrive; it does not need the sun's energy to work.
C. The ecosystem will look for a different source of energy to use.
D. The ecosystem will instantly stop working.
Answer:
A. The functions within the ecosystem will eventually stop & everything will die off.
Explanation:
Everything is dependent on the sun --starting from the bottom of the food chain, the producers. However, we wouldn't die instantly because "Earth retains heat fairly well, so humans wouldn't freeze instantly."
What variable represents specific heat in the equation Q = mcAT?
O A. The variable c
OB. The variable T
O C. The variable m
O D. The variable Q
Answer: A. The variable c
============================================
Explanation:
Q = heat transferred
m = mass
c = specific heat
[tex]\Delta T[/tex] = delta T = change in temperature
What is the percent composition by mass for hydrogen in water (H2O)?
% H =(_____/_____)x100%=______ % H
Explanation:
Percentage composition = 2/18 = 11.11%.
3. True or False: White light is a mixture of all colors of the visible
spectrum.
O True
False
it's true ....
plz mark my answer as brainlist plzzzz vote me also
Which substance below has the greatest intermolecular forces?
O oxygen with a boiling point of -183°C
O water with a boiling point of 100°C
O gold with a boiling point of 2,970°C
O mercury with a boiling point of 357°C
Answer:
Oxygen with a boiling point of -183°C.
Explanation:
Higher the intermolecular forces between the liquid particles, more durable it's for it to flee into the vapor part,you would like a lot of energy to convert it from liquid to the vapor part, in different words, higher its boiling point.
Hope it helps!<3
Word equation of almininum reaction with oxygen
Answer:
Aluminium + oxygen = almininum oxide
Hope it helps!! Please make me brainliest...
Merry Christmas good day
If you have 9.0x10^24 molecules of water, how many moles of water do you have?
Answer:
14.9 moles of water
Explanation:
Given data:
Number of molecules of water = 9.0×10²⁴ molecules
Number of moles of water = ?
Solution:
Avogadro number:
The given problem will solve by using Avogadro number.
It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.
The number 6.022 × 10²³ is called Avogadro number.
1 mole = 6.022 × 10²³ molecules of water
9.0×10²⁴ molecules ×1 mol / 6.022 × 10²³ molecules
1.49×10¹ moles
14.9 moles
*
When Gallium becomes an ion it loses 3 electrons to become:
A: -3
B: +3
C: It loses 3 electrons to become a neutral atom
D: It is already neutral
Answer:
B: +3
Explanation:
If Gallium loses 3 electrons, it will become an ion.
The ion will be positively charged because in this new ion, the number of electrons is lesser than the number of protons. The charge difference will impart a positive net charge on the ion.
In a neutral atom, the number of electrons and protons are the same. For positively charged ions, the number of protons is greater than the electronsIf Gallium the loss of 3 electrons offsets the charge balance in the chemical specie. Thus, the ion will have a net +3 charge.
Which has a higher melting point KF or NaF?
Answer:
NaF
Explanation:
Melting point of NaF is 993°C but Melting point of KF is 858°C
Answer:
I think naf
Explanation:
In order to determine if 2 atoms are cooper what must be the same for each
En un recipiente cerrado a 25°C disponemos de un gas sometido a una presión de 250.000 Pa. Luego, sin que cambie el volumen, conseguimos una presión de 350.000 Pa. ¿a qué temperatura habremos tenido que calentar el gas?.
Answer:
El gas se calentó a 35°C
Explanation:
Para resolver este problema es necesario aplicar la Ley de Gay Lussac donde en una situación en la que un gas no modifica su volumen, su temperatura será directamente proporcional a la presión.
Podemos pensar que se describe desde la Ley de Gases Ideales donde:
P . V = n . R . T
para la situacion 1
y P . V = n . R . T para la situacion 2
Como V, n y R son constantes:
P₁ / T₁ = P₂ / T₂
250000 Pa / 25°C = 350000 Pa / T₂
T₂ = 350000 Pa . 25°C / 250000 Pa → 35°C
what about solids ? Do solids move around like liquids and gases ?
Answer:
No, gases move freely all over the place, liquids move more freely but in a more contained area, and solids the molecules are rigid, at the most the movement is small vibration as the molecules put pressure on one another to hold their form and stay in place.
13. What is the frequency of a wave that has a wavelength of 2.73 x 10-7m?
Answer:
f = 1.09 × 10¹⁵ Hz
Explanation:
Given data:
Frequency of wave = ?
Wavelength of wave = 2.73 ×10⁻⁷ m
Solution:
Formula:
Speed of light = frequency × wavelength
speed of light = 3× 10⁸ m/s
by putting values,
3× 10⁸ m/s = f × 2.73 ×10⁻⁷ m
f = 3× 10⁸ m/s / 2.73 ×10⁻⁷ m
f = 1.09 × 10¹⁵s⁻¹
s⁻¹ = Hz
f = 1.09 × 10¹⁵ Hz
What object do you think will take up
more space? Why do you think this?
Answer:
solids
Explanation:
BC they r heavier than liquid and gas
What is the percent composition by mass for sodium (Na) in sodium phosphate (Na3PO4)? % Na = (______/______)x100% = _______% NNA
The percent composition by mass for sodium (Na) in Sodium phosphate (Na₃PO₄) : 42.07%
Further explanationGiven
Compound of Sodium phosphate (Na₃PO₄)
Required
The percent composition by mass for sodium (Na)
Solution
The Comparative Law (Proust ) : compounds are formed from elements with the same Mass Comparison
MW Na₃PO₄ = 163,94 g/mol
Ar Na=22,989769g/mol
[tex]\tt \%mass~Na=\dfrac{3.Ar~Na}{MW~Na_3PO_4}\times 100\%\\\\\%mass~Na=\dfrac{3\times 22.99}{163.94}\times 100\%\\\\\%mass~Na=42.07\%~Na[/tex]
HELP PLSSS FASTTTTTT!!!!!!!!!!!!!!!!
Answer:
with what?
Explanation:
What is mole concept? how to do its numericals
5. Calculate the time required to deposit 0.37g of Silver from a silverNitrate solution using a current of 2.5A( Charge of Ag in AgNO3 is + 1)
Time required : 132.2 s
Further explanationGiven
mass of Silver = 0.37 g
current = 2.5 A
Required
time do deposit
Solution
Faraday's Law :
[tex]\tt W=\dfrac{e.i.t}{96500}[/tex]
e = ar/valence (valence Ag = 1)
i = current
t = time = s
[tex]\tt 0.37~g=\dfrac{108/1\times 2.5~A\times t }{96500}\\\\t=132.2~s[/tex]
help me please... tyy if you do :))
Answer:
a) HCl
Explanation:
As we know, that HCl or Hydrogen Chloride is a diatomic compound. It is formed due to the Chemical reaction of Hydrogen and Chlorine. As both Hydrogen and Chlorine have valencies of 1, the Net Valency of the Compound HCl is 1 itself. This separates it from the rest of the compounds. The rest of the compounds need to have more than 2 atoms of each kind and have different valencies too.