Answer:
c
Explanation:
Cạnh của hình lập phương là
³\(125 = 5cm
Diện tích đáy của hình lập phương là
5²=25cm²
Đáp án C
9. During an experiment the students prepared three mixtures A)Starch in water B) Sodium chloride solution C) Tincture of Iodine. i) Students observed a visible beam of light through mixture A. Why? ii) Tincture of lodTe did not show Tyndall effect. Explain reason. ill) How can you relate particle size to Tyndall effect?
Answer:
See explanation
Explanation:
Tyndall effect refers to the scattering of light in a solution. Tyndall effect occurs when the size of particles in the solution exceeds 1 nm in diameter. Such solutions are actually called false solutions.
In tincture of iodine, the size of particles in solution is less than 1 nm in diameter hence the solution does not exhibit Tyndall effect. Hence, tincture of iodine is a true solution.
Therefore, if the size of particles in solution exceeded 1nm in diameter, Tyndall effect is observed.
What is the name of this molecule?
H3C - C ≡ C - CH3
Answer: 1,2,3, or 4-butyne?
Explanation:
The given molecule is
H3C - C ≡ C - CH3
The numbering order is shown below:
H3C - C ≡ C - CH3
1 2 3 4
So, the alkyne group is in the second position.
The carbon chain has four carbons.
Hence, the IUPAC name of the given compound is:
2-butyne.
If 16.4 grams of calcium nitrate is heated as shown in the reaction:
2Ca(NO3)2 -> 2CaO + 4NO2 + O2.
Calculate the volume of nitrogen dioxide produced at STP.
Answer:
7.2
Explanation:
you first have to find the number of moles of nitrogen dioxide by using the number of moles for calcium nitrate and the mole to mole ratios
number of moles of calcium nitrate=mass/mm
=16.4/102
=0.16g/mol
then you use the mole to mole ratios
2 : 4
0.16: x
2x/2=0.64/2
x=0.32g/moles of nitrogen dioxide
then you use the formula for the volume
v=22.4n
=22.4×0.32
=7.2
I hope this helps
Which fossil fuel is the remains of ancient plants?
A. Coal
B. Petroleum
C. Natural Gas
A. Coal
Others are animal remains
The fossil fuel which is the remains of ancient plants is: A. Coal.
Non-renewable energy can be defined as a type of energy that is mainly generated through artificial sources or from the remains of ancient plants.
Hence, a non-renewable energy cannot be replenished or renewed like the renewable energy sources.
Basically, some examples of a non-renewable energy include:
Natural gas.Petroleum.Coal.Other fossil fuels.Coal deposits are typically petrified peat swamps and peat is generated from decaying plants.
Also, coal has been discovered to be a fossil fuel that contain the remains of ancient plants, based on radioactive dating.
Read more: https://brainly.com/question/22527860
You mix the sample discussed in the previous two questions with another sample, which you know to be pure acetylsalicylic acid. You grind the mixture thoroughly with a mortar and pestle, and do a melting point determination on the mixed product. You now observe melting over a range of 127 to 133 C. Now what conclusions can you reach regarding the original product
Answer:
Having high melting point.
Explanation:
The original product has high melting point as compared to the mixture product because in the original product, the element is present in its pure state and we know that pure substances have high melting point as compared to mixture substances due to the presence of strong intercellular forces between them which is hard to break so that's why we can say that the original product has high melting point.
PLZ HELP Matthew wants to study how the body responds when the skin is broken. He learns that particles in the blood clump together at the site of the wound to stop the bleeding while the skin heals. Which of the following body systems is involved in carrying the blood to the site of the wound?
A. Cardiovascular
B. Skeletal
C. Respiratory
D. Muscular
Answer:
A, Cardiovascular system
cardiovascular system
calculate the maximum mass of ethanol that could be obtained from 30.0g of glucose
Answer:
15.3g
Explanation:
C6H12O6 → 2C2H5OH + 2CO2
1 mol C6H12O6 = 180g
1 mol CH3-CH2-OH = 46g
From 180g glucose ethanol can get = 92g
30g glucose ethanol gives us = (92*30)/180 = 15.33g
Which of the following elements would you expect to be most reactive, based
on the number of valence electrons it has?
Answer:
C. Lithium
Explanation:
This image describes the trend in reactivity. Group 1 metals are always the most reactive so yeah :)
calculate the mass of magnesium needed to make 25g of magnesium oxide
Explanation:
here's the answer to your question about
What is the solubility of salt at 60°C if 2 gm of the salt is left behind when 7 gm of its saturated solution at that temperature dried?
a) 20
b) 40
c) 60
d) 80
40
Explanation:
because its Saturated
A phase change from a solid to a gas is called:
Answer:
sublimation
Explanation:
CaCO3 + 2HCl > CaCl2 + CO₂ + H₂O
Explanation:
This reaction is also known as double decomposition reaction.
HCl + CaCO3 + MgCO3 → H2O + H2 + CO2 + CaCl2 + MgCl2
4. Magnesium is the limiting reactant in this experiment. Calculate the theoretical yield of MgO for each trial.
5. Determine the percent yield of MgO for your experiment for each trial.
6. Determine the average percent yield of MgO for the two trials.
Answer: The average percent yield of MgO is 98.59 %.
Explanation:
The chemical equation follows:
[tex]2Mg(s)+O_2(g)\rightarrow 2MgO(s)[/tex]
For Trial 1:The number of moles is defined as the ratio of the mass of a substance to its molar mass. The equation used is:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ......(1)
Given mass of Mg = 0.411 g
Molar mass of Mg = 24.3 g/mol
Plugging values in equation 1:
[tex]\text{Moles of Mg}=\frac{0.411g}{24.3g/mol}=0.0170 mol[/tex]
By the stoichiometry of the reaction:
If 2 moles of Mg produces 2 moles of MgO
So, 0.0170 moles of Mg will produce = [tex]\frac{2}{2}\times 0.0170=0.0170mol[/tex] of MgO
We know, molar mass of [tex]MgO[/tex] = 40.3 g/mol
Putting values in equation 1, we get:
[tex]\text{Mass of }MgO=(0.0170mol\times 40.3g/mol)=0.685g[/tex]
The percent yield of a reaction is calculated by using an equation:
[tex]\% \text{yield}=\frac{\text{Actual value}}{\text{Theoretical value}}\times 100[/tex] ......(2)
Given values:
Actual value of the product = 0.675 g
Theoretical value of the product = 0.685 g
Plugging values in equation 1:
[tex]\% \text{yield}=\frac{0.675g}{0.685g}\times 100\\\\\% \text{yield}=98.54\%[/tex]
Hence, the % yield of the product is 98.54 %
For Trial 2:Given mass of Mg = 0.266 g
Molar mass of Mg = 24.3 g/mol
Plugging values in equation 1:
[tex]\text{Moles of Mg}=\frac{0.266g}{24.3g/mol}=0.011 mol[/tex]
By the stoichiometry of the reaction:
If 2 moles of Mg produces 2 moles of MgO
So, 0.011 moles of Mg will produce = [tex]\frac{2}{2}\times 0.011=0.011mol[/tex] of MgO
We know, molar mass of = 40.3 g/mol
Putting values in equation 1, we get:
[tex]\text{Mass of }MgO=(0.011mol\times 40.3g/mol)=0.443g[/tex]
The percent yield of a reaction is calculated by using an equation:
[tex]\% \text{yield}=\frac{\text{Actual value}}{\text{Theoretical value}}\times 100[/tex] ......(2)
Given values:
Actual value of the product = 0.437 g
Theoretical value of the product = 0.443 g
Plugging values in equation 1:
[tex]\% \text{yield}=\frac{0.437g}{0.443g}\times 100\\\\\% \text{yield}=98.64\%[/tex]
Hence, the % yield of the product is 98.64 %
Average of a measurement is calculated by given formula:
[tex]Average=\frac{M_1+M_2}{2}[/tex]
where,
[tex]M_1[/tex] = percentage yield for Trial 1 = 98.54 %
[tex]M_2[/tex] = percentage yield for Trial 2 = 98.64 %
Putting values in above equation, we get:
[tex]Average=\frac{98.54+98.64}{2}=98.59\%[/tex]
Hence, the average percent yield of MgO is 98.59 %.
hii pls help me to balance the equation and state the symbols thanksss
Ca(s)+ H2O (l)----->H2 +Ca(oH)2
Ca(s)+2H2O(l)----->H2(g)+Ca(oH)2
I hope this helps
sorry if it's wrong
True or false, the four units that must always be used when using the ideal gas law are liters, atm, Kelvin, and grams
Answer:
False grams is not used
Explanation:
IDEAL GAS LAW
The ideal gas law states that PV = NkT, where P is the absolute pressure of a gas, V is the volume it occupies, N is the number of atoms and molecules in the gas, and T is its absolute temperature.
It is necessary to use Kelvin for the temperature and it is conventional to use the SI unit of liters for the volume. However, pressure is commonly measured in one of three units: kPa , atm , or mmHg . Therefore, R can have three different values.
The seedlings that we planted on the newspaper cuttings or cotton wool did not grow very well at all, even though they had sunlight and water. What could they not get from the newspaper or cotton wool that plants normally get from soil?
Question 6 of 10 What is the function of mitochondria? O
A. The mitochondria use sugars as fuel to produce energy.
B. The mitochondria direct the cell's activities and hold its DNA.
C. The mitochondria surround the cell and control which materials come into and out of the cell.
D. The mitochondria use sunlight to produce sugars. SUBE
Answer:
A. The mitochondria use sugars as fuel to produce energy.Explanation:
The most prominent function of mitochondria is to produce the energy currency of the cell, ATP (i.e., phosphorylation of ADP), through respiration and using sugar as fuel, and to regulate cellular metabolism .
what is mean by measurement
Answer:
Measurement is defined as the act of measuring or the size of something. An example of measurement means the use of a ruler to determine the length of a piece of paper. ... Extent, quality, or size as determined by measuring; dimension. A waist measurement of 32 inches.
Explanation:
The comparison o unknown quantity with known standard quantity is called measurement.
Oxit bazơ có những tính chất hóa học nào?
Answer:
tác dụng với acid,
Explanation:
If a pile of a deson of Buttons has a height of 2cm 4mm, what is the thickness of one to button.
The thickness of one button will be 2mm
According to this question, a pile of a dozen buttons has a height of 2cm 4mm. A dozen means 12, hence, 12 buttons has a height of 2cm 4mm.* N.B: We convert the height of the 12 buttons to same unit (mm)
Since 1cm = 10mmThen, 2cm = 2 × 10 = 20mm
20mm + 4mm = 24mm
That is, twelve buttons (a dozen) has a thickness of 24mm, one button will therefore, be:24/12 = 2mm thick
Hence, one button is 2mm thick.
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Which redox reaction would most likely occur if silver and zinc metal were
added to a solution that contained silver and zinc ions?
Click for a reduction potential chart
O A. Zn2+ + 2Ag → Zn + 2Agt
B. Zn2+ + 2Agt → Zn + 2Ag
C. Zn + 2Ag → Zn2+ + 2Ag+
D. Zn + Ag? → Zn2+ + 2Ag
Answer:
Zn²⁺ + 2Ag → Zn + 2Ag⁺
Explanation:
According to the reduction potential chart, silver ion (Ag⁺) is a stronger oxidizing agent than zinc (Zn), which is a reducing agent the compared to silver
Therefore, the redox reaction that will occur is that the zinc, Zn, will be oxidized to Zn²⁺ ion, while the silver, Ag²⁺ ion will be reduced to silver deposits Ag, therefore, the zinc will displace the silver in the solution containing silver and zinc ions because zinc is higher than silver in the reactivity series
The reduction potential Zn → Zn²⁺ + 2e⁻ = +0.76
The reduction potential for Ag⁺ + e⁻ → Ag = +0.8
Given that redox reactions are reversible, we get the following likely redux reaction:
Zn(s) + 2Ag⁺(aq) ⇄ 2Ag(s) + Zn²⁺(aq)
Zn²⁺(aq) + 2Ag(s) → Zn(s) + 2Ag⁺(aq) is the reaction most likely to occur.
which of the following statements is true about alkali?
A) bases that soluble in water
B) shows a pH value less than 7
C) Ionises in water to form hydroxonium ions
D) Reacts with carbonate salt to release carbon dioxide gas
Answer:
it should be letter c
Explanation:
I hope this help
Which is the best term to use when describing the energy of motion? chemical kinetic potential thermal
Answer:
Kinetic energy
Explanation:
Kinetic energy is the energy associated with an object's motion. It is mass and velocity dependent by a directly proportional relationship.
Potential energy is the energy associated with an object's position.
Thermal energy is the energy associated with heat addition or withdrawal.
Kinetic energy is the energy that a body possesses because of its movement, that is, it is the energy that arises when objects are in motion.
What is kinetic energy?It is that energy that a body or system possesses due to its movement.The amount of work done by all the forces acting on a body with a given mass, depends on the said mass and the speed of the body.Therefore, we can conclude that kinetic energy is the energy produced by its movements that depends on its mass and speed.
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Give reasons. a. Troposphere is affected maximum by human activities.
Answer:
it is where the ozone layer is locate which is affected by human activities
A solution, such as pure water, with a pH of 7 contains which of the following?
a. Dissolved CO2
b. Equal amounts of hydrogen ions and hydroxide ions
c. Smokestack pollutants such as sulfur dioxide
d. Sodium hydroxide
Answer:
B
Explanation:
Pure water always has equal concentrations of hydrogen and hydroxide ions.
Consider two gases, A and B, which are in a container at room temperature. What effect will the following changes have on the rate of the reaction between these gases?
The temperature is decreased at a constant volume.
A. Increase
B. Decrease
Answer:
A. The rate of reaction will increase or go up
B. The rate of reaction will decrase or go down.
Explanation:
Increasing the temperature will make the gas particles move faster. Faster movement will increase rate of collision between particles to cause a reaction. Decreasing the temperature will cause the opposite to happen.
state the modern periodic law
Answer:
The modern periodic law states that the physical and chemical properties of the elements are the periodic function of the atomic numbers and electronic configurations. ... This repetition occurs if the arrangement of the elements is in order of their increasing atomic numbers.
Any individual offspring produced through a sexual reproduction is always,
Answer:
Any individual offspring produced through asexual reproduction is always: genetically identical to its parent. made up of cells with a cell wall. different from all of its siblings
C4H9OH have several isomers. Draw structure and IUPAC names of its three isomers.
Answer:
.
Explanation:
A sample of lithium sulfate, (Li2SO4), has 2.94 x 1023 atoms
of lithium. How many moles of lithium sulfate is the sample?
Answer:
0.245 moles
Explanation:
moles of lithium = 2*moles of Li2SO4
so moles of LI2SO4=2.94*10^23/(2*6*10^23)=0.245
One mole of lithium sulphate contains 1.2 .022 × 10²⁴ atoms. Thus, the number of moles of this compound which contains 2.94 × 10²³ Li atoms is 4.08 moles.
What is one mole?Any substance containing 6 .022 × 10²³ number of atoms is called one mole of that substance. This number is called Avogadro number. Hence, one mole of every elements or molecules contains Avogadro number of atoms.
Similarly, one mole of any compound contains 6 .022 × 10²³ molecules. The weight of one mole of a compound is called its molar mass. The mass of one mole of an element is called its atomic mass.
Hence, one mole of lithium sulphate contains 2 × 6 .022 × 10²³ atoms of lithium. Therefore, the number of moles of lithium sulphate containing 2.94 × 10²³ Li is :
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