Answer:
95
Explanation:
94.5 contains 3 significant figures so to round it to just two, we can just round the number to the nearest whole number. Remember that we round up if we have 5 and up then we would round down if we have 4 and below.
94.5 → 95
Best of Luck!
a radioactive element has a half-life of 30 days. calculate the mass of the element that remains after 20 days if 100g of the element decays. Also, calculate the decay constant.
Answer:
A=Ao(1/2)^t/h
A=(100)(1/2)^20/30
A=63g
Engineers use scientific knowledge to help them design solutions to problems. GUK (sodium polyacrylate) is a chemical with some unusal properties. Think of a community problem or a global problem that could benefit from the properties of GUK. Discuss your vision of how GUK could be used to solve this problem in 3-5 sentences.
Sodium can be used to solve the problem of
Water pollutionSodium polyacrylate is a sodium salt of polyacrylic acid. It is a super absorbent polymer (SAP) that has great adsorption abilities enabled by the presence of sodium. These abilities find great application in many consumer products as it solves a lot of problems.
Metal ions can be removed from water in industries and water bodies using sodium polyacrylate because it has the ability to increase the surface area of porous substances so that there can be more transfer of mass.
Summarily, the problem of metal ions in water which causes pollution can be solved using GUK.
Learn more about sodium polyacrylate here:
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Carbonic acid weathering limestone
a
Chemical Change
b
Physical Change
If you mix sand and water in a container the sand will sink to the bottom. explain why
Answer:
Sand is heavier than water and cannot float in water, so it will sink to the bottom.
A gas occupies 250mL, and it's pressure is 0.724 atm at 25 degrees c.r = 0.0821 L•atm/mol•k. Solve for moles !! Plzzzz
Answer:
0.0074 moles
Explanation:
We'll have to use this forumla: PV = nRT
P = Pressure (0.724)
V = Volume in liters (0.25)
n = moles
R = 0.0821
T = temperature in kelvins (25 + 273 = 298)
Our equation will look like this:
(0.724)(.25) = n(0.0821)(298)
0.181 = 24.4658n
Divide both sides by 24.4658 to isolate n
0.181/24.4658 = 24.4658n/24.4658
n = 0.00739808
Cordell bought new tires for his bicycle. As he rode his bike on the hot street, the temperature of the air in the tires increased. If the volume of the air stayed the same, what happened to the pressure inside the tires?
Answer:
the pressure increased
An ice wedge shattering a slab of shale
a
Chemical Change
b
Physical Change
Answer:
Physical Change
Explanation:
Its a physical change because it is not changing its molecular structure it is only changing the shape of the shale.
ANSWER QUICK PLEASE!!!! 25 POINTS
Acrylonitrile and ethyl acetate have the same boiling point: 77.2ºC. In one to two sentences, explain what outcome you would expect if a mixture of these two substances were distilled.
The two substances can never be separated by distillation because distillation depends on difference in boiling point.
Distillation is a separation method that depends on difference in boiling point between two substances.
Usually, the substance having a lower boiling point is collected first as the temperature is gradually raised. The substance having a higher boiling point then follows.
However, since the two substances have the same boiling point, they can not be separated by distillation because they will be converted to vapor simultaneously thereby making separation impossible.
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EASY 30 POINTS! PLS HELP ME T-T
1. True or false? All atoms in an element contain an identical number of neutrons.
2. An atom with a _______ charge has the same number of protons and electrons.
3. An atom that has a different number of electrons and protons is called a(n) _______.
Answer:
1.false
2.neutron
3.neutron
Answer:
1. false
2. zero
3. isotopes
hope it helps
a current of 1.5 a is flowing through a 4 resistor.
Answer:
than what can i do lol
A student reacts 3.0 g of magnesium with 2.5 mol / dm3 sulfuric acid.Calculate the minimum volume of sulfuric acid that reacts with all the magnesium
3.og idbj mass of mjemantg 2.oml
What does the atomic number of an element represent?
A. number of isotopes
B. number of protons
C. number of bonds
D. number of atoms
Answer:
protons
Explanation:
btw you protons and electrons are always the same
prcAnswer:
e c. proton
Explanation:
i pueslist
How many kilojoules are required to raise the temperature of a 150. g sample of silver from 25 °C to 135 °C? Silver has a specific heat of 0.235 J/g °C.
Answer:
3.8775 kJ
Explanation:
The formula is Q=mcdeltat
We know m (mass) is 150, c (specific heat) is 0.235, and delta t (change in temperature) is 135-25=110
Plug that in and solve for Q
150*0.235*110=3877.5 J
The problem is that this is still in joules so we have to convert to kilojoules
3877.5 J * 1 kJ/1000 J = 3.8775 kJ
A hot chunk of metal at 120 degrees Celsius is put into water at 20 degrees Celsius.
What will happen to the temperatures of the materials?
A. metal and water will both end up at 140 °C
B. metal and water will both end up at 60 °C
C. metal temperature will decrease to 20 °C
D. water temperature will increase to 120 °C
i believe the answer is B: both wind up at 60°C
but it's also reasonable to assume, given enough time, they wind up at 20°C because the water would heat up to cool the metal then slowly release the heat to the air untill they both reach 20°C
if it were me I'd answer B, apologies if I'm wrong
GIVING 20 POINTS // SEP Analyze Data - The properties of matter can be classified into two groups. Extensive properties vary with the amount of matter in a sample. Intensive properties remain the same, or are independent of the amount of matter present. Analyze the data in the table to identify examples of extensive and intensive properties. Explain your classifications.
Answer:
Intensive Properties: Appearance, State, Reactivity, Density
Extensive Properties: Mass, Volume
Explanation:
Intensive Properties: Appearance, State, Reactivity, and Density values all stay the same, regardless of the amount of material.
Extensive Properties: Mass, and Volume depend on the amount of material present
Mass and volume are extensive properties.
Physical state, densities, appearances, and reactivities are intensive properties.
Explanation:
Extensive properties are those properties that depend upon the mass of the matter of substance. Cannot be used to identify the substance Intensive properties are those properties that do not depend upon the mass of the matter of substance. Can be used to identify the substanceIn the table given, we can see:
The mass and volume of even the same elements are differing this is because the amount of matter present in them is different.Mass and volume are extensive properties.
The physical state, densities, appearances, and reactivities of the respective elements are very much similar to their kind which means that these properties are not dependent on the size or volume of the elements.The physical state, densities, appearances, and reactivities are intensive properties.
Learn more about properties of the matter here:
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the nucleus of an atom is positively charged why
Answer:
hello ~~
look nucleus is mixture of neutrons and protons.. right?
and we know neutrons have no charge and protons are positively charged so overall charge of nucleus is positive
What is the density of an object that has a mass of 5.8g and a volume of 2.1 mL?
Answer:
[tex]\boxed {\boxed {\sf 2.8 \ g/mL}}[/tex]
Explanation:
Density is an object's mass per unit volume. The formula for calculating density is:
[tex]\rho= \frac{m}{v}[/tex]
The mass of the object is 5.8 grams and the volume is 2.1 milliliters.
m= 5.8 g v= 2.1 mLSubstitute the variables into the formula.
[tex]\rho = \frac{5.8 \ g}{2.1 \ mL}[/tex]
Divide.
[tex]\rho = 2.761904762 \ g/mL[/tex]
The original values of mass and volume (5.8 and 2.1) have 2 significant figures, so our answer must have the same. For the number we calculated, that is the tenths place. The 6 in the hundredth place tells us to round the 7 in the tenth place up to an 8.
[tex]\rho \approx 2.8 \ g/mL[/tex]
The density of the object is approximately 2.8 grams per milliliter.
How is the atomic mass of an element determined?
A. by adding the masses of the protons and electrons
B. by adding the masses of the neutrons and electrons
C. by determining the number of protons
D. by adding the masses of the protons, neutrons, and electrons
Answer:
D
Explanation:
Atomic mass is the total mass of protons, neutrons and electrons of an atom at rest
Which of following affects liquifaction of gases except
(2 Points)
Melting point
Volume
Temperature
Pressure
Answer:
pressure
Explanation:
gas convert to liquid at high pressure.
Balancing oxidation-reduction reactions
Mg+ N2—>Mg3N2
Answer:
[tex]{ \sf{3Mg_{(s)} + N_{2(g)} →Mg _{3}N_{2(s)}}}[/tex]
A school bus travels 40 kilometers in 1 hour. What is the appropriate unit for the average speed of the school bus?
Answer:
The average speed is = 11.1m/s
Explanation:
Recall that average speed is defined as the total distance traveled with respect to the total number of time, therefore we say that the total distance traveled is 40Km according to your question, remember, the unit of speed is metre per second, so you change 40km by multiplying it with 1000, recall that, 1000m = 1km, so 40km×1000m = 40,000m, also 1h= 60×60, =3600s
Remember the formula for average speed is = Total distance traveled÷ total time taken
Thus; 40000m/3600s
Then we had, 11.1m/s...
You can ask questions
Would you categorize temperature as an Intensive or extensive property explain plz !!!
Extensive properties depend on the amount of matter in a sample, While Intensive properties do not depend on the amount of matter in a substance.
~what is combination reaction give two examples
this table resembles a condensed version of the modern periodic table. using the full periodic table as a reference, type the symbols for the elements from part A into this table based on their appropriate group and period.
Explanation:
H, He ---------
Li, Be, --,C, F, Ne
Na, Mg, --,Si, Cl, Ar
K, Ca, Cu, Ge, Br, Kr
Rb, Sr, Ag, Sn, I, Xe
Cs, Ba, Au, Pb, At, Rn
Please give brainliest, I spent a lot of effort on this.
You want to determine the effect of a certain fertilizer on the growth of orchids grown in a greenhouse.
Materials that are available to you include: greenhouse, 100 orchid plants, water, fertilizer, and soil. You
want to know if the orchids will hgrow best with a weak concentration of fertilizer, a medium concentration
of fertilizer, or a high concentration of fertilizer. How will you design an experiment to test different
concentrations of this fertilizer?
how do you set up a controlled experiment
What are the uses of hydrogen?
Answer:
Hydrogen finds a variety of application due to its dual nature. Following are some important uses of hydrogen:
Hydrogen is used in the synthesis of ammonia and the manufacture of nitrogenous fertilizers.
Hydrogenation of unsaturated vegetable oils for manufacturing vanaspati fat.
It is used in the manufacture of many organic compounds, for example, methanol.
Hydrogen chloride is a very useful chemical and is prepared from hydrogen.
Hydrogen can reduce many metal oxides to metals by metallurgical processes.
Hydrogen is used as rocket fuel in many space research activities.
Hydrogen fuel is being experimented within the automotive industry with hydrogen fuel cells.
Could someone plz help me? Giving brainliest
Answer:
its D
Explanation:
A and C are ruled out because an opnion of scientist doesnt make the a law and B is not always true
Nitrogen oxide emissions combine with water vapor, producing nitric acid
a
Chemical Change
b
Physical Change
Answer:
chemical change
I hope it's helps you
If particles of a solid move slow and particles of
a gas move fast, which would have higher
kinetic energy (KE)?
Answer:
The gas particles would have higher Kinetic energy.
Explanation:
From the formular of kinetic energy:
[tex]{ \sf{KE = \frac{1}{2}m {v}^{2} }}[/tex]
KE is the kinetic energy possessed by particle.
KE is the kinetic energy possessed by particle.m is the particle mass.
KE is the kinetic energy possessed by particle.m is the particle mass.v is the velocity attained by a particle
[tex]{ \sf{KE = \{ \frac{1}{2} m \}} {v}^{2} }[/tex]
keeping the mass, m constant:
[tex]{ \sf{KE = k {v}^{2} }}[/tex]
Therefore, KE is directly proportional to v² :
[tex]{ \sf{KE \: \alpha \: {v}^{2} }}[/tex]
so, when velocity increases, KE also increases.
I don't know what to do...
from my thinking. you should find a solid..then try finding its volume.