Answer:
1.686 × 10²⁴ atomsExplanation:
The number of silicon atoms can be found by using the formula
N = n × Lwhere n is the number of moles
N is the number of entities
L is the Avogadro's constant which is
6.02 × 10²³ entities
From the question we have
N = 2.8 × 6.02 × 10²³
We have the final answer as
1.686 × 10²⁴ silicon atomsHope this helps you
A 20 N object is placed on a surface and starts to slide. What is the MOST likely reason the object begins to move?
A O Gravity exerts a balanced force on the object.
В.
Friction is applied to the object.
c. An unbalanced force causes acceleration.
D
The forces acting on the object are in equilibrium.
Answer:
c.
Explanation:
If the object starts to slide it must be on a slope.
There are 2 forces acting on the object - gravity and the friction between the object and the surface.
If sliding starts then the forces must be unbalanced.
The force of gravity is greater than the friction.
Answer:c
Explanation:
13. The quality of petrol as an engine
fuel improves with a higher amount
of
A. branched chain alkanes.
B. branched chain alkenes.
C. branched chain alkynes.
D. straight chain alkynes.
E. straight chain alkynes.
Answer:
The correct option is;
A. Branched chain alkanes
Explanation:
By the process of cracking of petroleum, higher quality petrol are formed by converting straight chain petrol to branched petrol, which are the grade of petrol that burns more smoothly and therefore efficiently within internal combustion engines
The cracking process includes;
a) The conversion of alkanes which are large molecules into branched octanes
b) The conversion of alkanes with straight chain into branched chain alkanes
c) The formation of a branched chain alkane and an alkene from straight chain alkanes
d) The formation of branched chain alkane and hydrogen gas from a straight chain alkane.
Margarita set up three vials on a hot plate. She poured the same amount of
liquid into each of the vials, and then she turned on the hot plate. Which event
could be a significant source of error in her experiment?
Answer: Since the vials are filled the same, and are placed on the same hot pad, all the water will evaporate at the same time
Explanation:
The source of error in the experiment is the vials being filled the same, and placed on the same hot pad, all the water evaporating at the same time .
What are errors?Errors in chemical analysis result when there is a difference between observed value and the true value.If the magnitude of errors is large , it results in decrease in accuracy, reproducibility, and precision.
There are three types of errors:1) random error 2) systematic error 3) human error.The cause of random errors are difficult to quantify while the human errors can be minimized by taking a range of readings to reduce the error.
Errors while measuring boiling point may be human errors while noting down the boiling temperature or instrumental or systematic error if there is a fault in the thermometer.
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write the metals and nonmetals and metalloids in the first 30 elements
Answer: Metals: Li, Be, Na, Mg, Al, K, Ca, Sc, Ti, V, Mn, Fe, Co, Ni, Cu, Zn
Non-metals: H, He, C, N, O, F, Ne, Si, P, S, Cl, Ar
Metalloid: B
Explanation: The first 30 elements are H, He, Li, Be, B, C, N, O, F, Ne, Na,
Mg, Al, Si, P, S, Cl, Ar, K, Ca, Sc, Ti, V, Mn, Fe, Co, Ni, Cu, Zn
Metallic elements are more electropositive (tending to form ions by donating electrons) with fewer electrons in their outer shell
Non-metallic elements are more electronegative (tending to form ions by accepting electrons) with more electrons in their outer shell
Metalloids are elements somewhere between, but without any specific clear boundary between them and metals/non-metals
group1 and group2 elements, with one or two outer electrons, are all metals: Li, Na, K, Be, Mg, Ca
similarly the transition metals 21-30 are all electropositive and metals.
The noble gases He, Ne, Ar are gases that have completed outer shells and are non-metallic, likewise the halogens F, Cl with 7 outer electrons, and O and S with 6 are non-metals. N and P (5 outer electrons) are non-metallic as are C and Si (4 outer electrons).
This leaves H, B, Al. H, with its single electron close to the nucleus is a non- metallic gas. Al (3 outer electrons) is metallic, but B, has its 3 electrons close to the nucleus and has the in-between character of a metalloid.
why sodium and chlorine are active element
How much radium-226 will remain from a 20 gram sample after 4800 years?
Answer:
2.5 g mass of Ra-226 will remain after 4800 years.
Explanation:
Given data:
Mass of Ra-226 = 20 g
Sample remain after 4800 years = ?
Solution:
Half life of Ra-226 = 1600 years
Number of half lives passed = T elapsed / half life
Number of half lives passed = 4800 year / 1600 year
Number of half lives passed = 3
At time zero = 20 g
At first half life = 20 g/2 = 10 g
At 2nd half life = 10 g/2 = 5 g
At 3rd half life = 5 g/2 = 2.5 g
Thus, 2.5 g mass of Ra-226 will remain after 4800 years.
teapot filled with water is heated on the stove. What does the heat from the stove do to the molecule of water in the teapot?
Answer:
The kettle on the stove takes thermal energy from the stove and uses it to convert water into steam at constant temperature. The molecules of water vibrate with increasing speeds when the temperature of water increases. When the temperature of water reaches the boiling point, water starts to change its state to steam.
Explanation:
If 0.20 bushel is 1 dozen apples and a dozen apples has a mass of 2.0 kg, what is the mass of 0.50 bushel of apples?
Answer:
Mass of 0.50 bushel = 5 Kg
Explanation:
Given data:
Number of apples in 0.20 bushel = 1 dozen
Mass of 1 dozen apple = 2.0 Kg
Mass of 0.50 bushel apple = ?
Solution:
First of all we will calculate the number of dozen of apple in 0.50 bushel.
(1/0.20) ×0.50 = 2.5 dozen
Mass of 0.50 bushel = 2.5 dozen × 2.0 Kg/1 dozen
Mass of 0.50 bushel = 5 Kg
Drag and drop the correct component and reactants to fill in the equation for photosynthesis
Answer:
6CO2 + 6H2O ----> C6H12O6 + 6O2
Explanation:
Photosynthesis is the process by which green plants manufacture their own food using sunlight in the presence of carbon dioxide water and chlorophyll.
Chlorophyll is the pigment in plants that absorbs light.
The equation of photosynthesis is shown in the answer section above. Sugar and oxygen are the first products of photosynthesis.
a school bus drives 35 mph down the street and slows as it approaches the stop sign
Which of the following would increase the intensity of the tornado?
a. decrease in wind speed
b. decrease in condensation
c. increased rate of evaporation
d. increase of cold air
The tail in figure A and the rings in figure C are held together by a similar force. What force holds the tail and the rings together?
Answer:
It has to be weak vander waal's forces of attraction.
Answer:
The tail and the rings are held together by the force of gravity.
Which is the vector quantity that describes the shortest path between two points?
The shortest distance taken by the object to reach the destination at a minimum time is called acceleration. Thus value acceleration depends upon the displacement and time.
why is a frozen popsicle a homogeneous mixture and not a pure substance
Answer:
You can not see the sugar.
Explanation:
22.
An example of amphoteric oxide is
A. Al2O3.
B. CaO.
C. Cuo.
D. SiO2.
E. K20.
Fu** please help
Answer:
A (option) .............
Answer:
Al2O3
Explanation:
ZnO,Al2O3,PbO2 are some of the amphoteric oxides
Amphoteric oxides are metal oxides that can react with both acids and bases,so Aluminum oxide can react with both HCl and Sodium hydroxide which is a base
Which increases along faults and leads to rock breaking? damage earthquake focus stress
A. damage
B. earthquake
C. focus
D. stress
Answer:
Stress
Explanation:
Stress increases along faults and leads to rock breaking. Therefore option D is correct.
Along faults, stress builds up in the rocks due to the movement and interaction of tectonic plates. Stress is the force applied to the rocks, and it can occur in various forms, such as compression, tension, or shear. As the stress increases, the rocks become more strained and are pushed to their breaking point.
When the stress exceeds the strength of the rocks, they can no longer withstand the applied forces and break, resulting in an earthquake. The release of accumulated stress along the fault causes the rocks to rupture and generate seismic waves, leading to ground shaking and the propagation of energy throughout the Earth's crust.
Therefore, stress is the primary factor that increases along faults and ultimately leads to rock breaking and the occurrence of earthquakes.
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Theresa creates an experiment where she mixes two red-colored substances together in a container and observes the solution slowly changing from red to blue for the next eight minutes. The solution becomes completely blue after eight minutes. What does this represent about the type of change happening in the container?
Complete Question:
Theresa creates an experiment where she mixes two red-colored substances together in a container and observes the solution slowly changing from red to blue for the next eight minutes. The solution becomes completely blue after eight minutes. What does this represent about the type of change happening in the container?
Group of answer choices
A. A chemical change started immediately and finished at eight minutes.
B. A non-chemical change started immediately and finished at eight minutes.
C. A chemical change occurred at four minutes.
D. A non-chemical change occurred at four minutes.
Answer:
A. A chemical change started immediately and finished at eight minutes.
Explanation:
A chemical reaction can be defined as the chemical process which typically involves the reaction between two or more chemical elements (substances) to form a new compound, through the rearrangement of the ionic or molecular structure of each chemical element.
This ultimately implies that, a chemical reaction is a chemical change that immediately starts when two or more molecules of a chemical element (substance) known as reactants are combined together to form a new product (compound).
In this scenario, Theresa creates an experiment where she mixes two red-colored substances together in a container and observes the solution slowly changing from red to blue for the next eight minutes. The solution becomes completely blue after eight minutes. Thus, what this represent about the type of change happening in the container is that, a chemical change (from red to blue) started immediately and finished at eight minutes.
why is the symbol Ar used in the electron configuration of potassium, and what does it represent?
Answer:
It represents the noble gas that precedes the period before Potassium.
Explanation:
Period before potassium is 3, the noble gas in that period is Ar (Argon). So when condensing the electron configuration of Potassium, Argon can account for 18 electrons instead of writing out 18 electrons in full form from 1s2, 2s2 etc.
Displacement can be added to get the total
a) velocity
b) distance
c) speed
d) acceleration
Convert 76.8 cm to m.
Answer:
0.768 m
Explanation:
1 cm = 0.01 m
76.8 cm * 0.01 m/ 1 cm
0.768 m
Which has a higher frequency: microwaves or blue light? How do you know?
Answer:
Microwaves
Explanation:
Microwaves have more energy than blue light
Among microwaves or blue light, blue light has a higher frequency. This is because blue light belongs to the visible region has a short wavelength and produces a higher amount of energy.
What is the relationship between frequency and wavelength?The frequency of any wave is inversely related to the wavelength. This means that when the frequency of the wave increases, the wavelength decreases. While the relationship between frequency is directly related to the energy.
According to the context of this question, gamma rays have the highest frequency and shorter wavelength, while radiowaves have a shorter frequency and the highest wavelength.
Therefore, blue light has a higher frequency. This is because blue light belongs to the visible region has a short wavelength and produces a higher amount of energy.
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7. Base your answer to the following question on the information below and on your knowledge of biology A student designed an experiment to investigate a claim that athletes would have lower heart rates than nonathletes during exercise. After the students classified themselves as an athlete or a nonathlete, their resting pulses were determined. Then all the students performed the same exercise for four minutes and their heart rates were determined by recording the pulse rate in beats per minute. The students continued to measure their pulse rates for an additional four minutes. The average heart rate per minute for each group was determined. The data were recorded, as shown on the table below Average Heart Rate Response to Exercise (beats per minute) Time (minutes) Athlete Students Nonathlete Students Resting Pulse 68 72 1 76 78 2 82 90 Exercising Period 3 115 95 110 4 130 5 100 125 6 95 120 After Exercise 7 85 100 8 68 95 2.4 To improve the validity of the conclusion reached in this experiment, the students should repeat the experiment A) disregarding any data that don't fit the hypothesis B) with a larger number of athletes and nonathletes C) comparing the heart rates and breathing rates of males and females D) with the athletes doing different exercises than the nonathletes
when it is cold in your house
Answer:
yep.
Explanation:
I love to wear oversized hoodies and I get soft comfy blankets and watch movies. Have a nice night! :)
2CuO+2NH3------ 3Cu + 3H2O+ N2. Given that the relative molecular mass of copper oxide is 80, what volume of ammonia is required to completely reduce 120 g of Copper oxide? ( Cu=64, O=16, N=14)
Volume of Ammonia(NH₃) = 22.4 L
Further explanationGiven
Reaction
3CuO+2NH₃⇒ 3Cu + 3H₂O+ N₂
In the problem, the CuO coefficient should be 3 not 2
M CuO = 80
mass CuO = 120 g
Required
The volume of NH₃
Solution
mol CuO :
[tex]\tt mol=\dfrac{mass}{M}\\\\mol=\frac{120}{80}\\\\mol=1.5[/tex]
From the equation, mol ratio CuO : NH₃ = 3 : 2, so mol NH₃=
[tex]\tt \dfrac{2}{3}\times 1.5=1~mol[/tex]
Assume at STP(0 °C, 1 atm) ⇒1 mol = 22.4 L, then volume of NH₃=22.4 L
An allotrope of carbon that is structured in a sphere is called:
A. fullerene
B. tetrahedron
C. graphite
D. diamond
Answer:
fullerene
Explanation:
Do you think it would be a good idea for a bumper car ride to have minimum and maximum weight requirements for riders? Apply Newton's second and third laws of motion in your response.
Answer: If only max or min yes but if we have min and max that is a bad idea it is not as safe.
Para preparar 1 kilogramo de arcilla se requieren 400 gramos de agua. Si a nivel del laboratorio solo se cuenta con una probeta y sabemos que la densidad del agua es 1100Kg/m3 ¿Cuántos litros de agua se deben añadir?
Answer:
0.364 L
Explanation:
Para resolver este problema es necesario expresar la densidad en g/L.
Para hacer esa conversión primero convertimos m³ en L:
1 m³ = 1000 L1100 [tex]\frac{kg}{m^3}* \frac{1m^3}{1000L}[/tex] = 1.1 kg/LY después convertimos kg en g:
1.1 kg/L * [tex]\frac{1000g}{1kg}[/tex]= 1100 g/LFinalmente dividimos la masa deseada (400 g) entre la densidad, para calcular el volumen:
400 g ÷ 1100 g/L = 0.364 LPLEASE HELP DUE IN EXACTLY 15 mins!! i will give you branliest
[tex]2032533 \sq22222rt[2]{?} [/tex]
Qu 4.
How many protons, neutrons, and electrons are present in an atom of gold, Au,
with a mass number of 197?
197 protons, 276 neutrons, 79 electrons
79 protons, 118 neutrons, 79 electrons
Du Do
79 protons, 197 neutrons, 118 electrons
&
118 protons, 72 neutrons, 118 electrons
Answer:
It's the second one down.
Explanation:
Gold
Mass 197
Number of Protons: 79
Number of Neutrons: 197 - 79 = 118
Number of electrons: = number of protons = 97
1. Solve for x
Atomic number 31
Atomic mass x
Number of protons y
Number of neutrons 33
Number of electrons 28
Charge of element z
Answer:
Atomic mass = proton + neutron
31+33= 64
Number of proton = Atomic number = 31
Charge of element is +3
Explanation: