Answer:
The FitnessGram™ Pacer Test is a multistage aerobic capacity test that progressively gets more difficult as it continues. The 20 meter pacer test will begin in 30 seconds. Line up at the start. The running speed starts slowly, but gets faster each minute after you hear this signal. [beep] A single lap should be completed each time you hear this sound. [ding] Remember to run in a straight line, and run as long as possible. The second time you fail to complete a lap before the sound, your test is over.
Cuales son los tipos de yemas
2. Low-density polyethylene, used to make plastic films, is
made by the radical polymerization of ethene, and is one of
the hardest plastics to recycle. It gets its name
A. from the process by which it's polymerized.
B. because of the way the chains pack like spaghetti, close
and tight.
C. from the spaces left between chains when the polymer is
formed.
D. because it's strong but flexible.
Answer:
from the spaces left between chains when the polymer is
formed.
Explanation:
Polyethylene polymer may be of high or low density. Whether the polymer is of high or low density depends on the arrangement of the polymer chains.
If the polymer chains are close together such that the resultant polymer is crystalline with chains packed closely, we have high density polyethylene.
On the other hand if the chains are not close together and there are spaces left between chains when the polymer is formed, then we have low density polyethylene.
Hence, low density polyethylene gets its name from the spaces left between chains when the polymer is formed.
Answer: it gets its name (from the process by which it's polymerized). Therefore the correct option is A.
Explanation:
Polyethylene is a type of plastic which is made by the polymerization of its monomers (ethene). The most common monomers are derived from petrochemicals. The monomers simply join together to form the polymers which has the same empirical formula as the monomer, but is of a higher molecular mass.
There are two main types of polyethylene, these include:
--> Low density polyethylene: when ethene is subject to a high temperature of about 250°C and pressure above 1500atm, together with traces of oxygen ( as an initiator), it polymerizes to polyethylene. The polyethylene obtained by the above method is called a low density polyethylene. It has the most long- and short-chain branching of any form of polyethylene, resulting in its lower density. Therefore its name is gotten from the process by which it's polymerized
--> High density polyethylene: this is prepared at a lower temperature and pressure by using catalysts.
1a.calculate the relative formula mass of magnesium oxide when the relative atomic masses are O=16 Mg=24
1b.calculate the percentage by mass of magnesium in magnesium oxide
here's the answer to your question
The relative mass of the magnesium oxide (MgO) is equal to 40 g. The percentage by mass of magnesium in MgO is 60 %.
What is the mass percentage?The mass percentage of any element in a particular compound can be calculated from the number of parts by mass of the element in 100 parts by mass of a given compound.
Calculate the molar mass of the given compound by adding the atomic masses of the present elements. Then, the percentage of each element can be determined by dividing the total mass of the element by the molar mass of the compound multiplied by 100.
Given, the molecular formula of magnesium oxide is MgO. The atomic mass of Mg and O is 24 g and 16 g respectively.
The relative formula mass of the MgO = 40 g/mol
The mass percentage of the Mg = (24/40) × 100 = 60 %
Therefore, the mass percentage of the Mg in MgO is equal to 60 %.
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Describe how a constant volume calorimeter can be used to measure the heat transferred from a burning piece of coal to cool water.
thank you <3
Answer:
A Calorimeter is a device used to measure the amount of heat involved in a chemical or physical process.
Explanation:
Ex- when an exothermic reaction ( accompanied by or requiring absorption of heat)occurs in solution in a calorimeter, the heat produced by the reaction is absorbed by the solution increasing its temperature.
- When an endothermic reaction (Heat evolving reaction) occurs, the heat required is absorbed from the thermal energy of the solution, decreasing its temperature.
A burning piece of coal which is releasing heat due to its combustion and is transferred to water.
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Write the relation of M3 with its multiples
Explanation:
HI friends good morning
Is it possible to prepare chlorine in lab without application of heat?
Answer:
i think it will explode
Convert solar day into mintues
Answer:
There are 24*60 minutes in a day (ignoring the imperfections of the natural world, the Earth and Sun). So there are 24*60 valid 24 hour times (excluding seconds) on a digital clock.
A measure of time representing the interval between consecutive passages of the Sun across the meridian, averaged over one year. 1 day = 24 hr (86,400 sec) and 60 minutes.
hope it helps ya mate! :-P
Matty told Harriet that, later that same day, he was going to try to convince her to change her attitude toward the nutritional merits of doughnuts. Based on research findings regarding persuasion, how effective is Matty's strategy?
Answer:
The correct answer is - not very effective; forewarning tends to reduce the effectiveness of an attitude change
Explanation:
The strategy of forewarning or warning before attempting any change in the psychology of an individual is found to be less effective. The subject sees a forewarning seen as a warning that a person is going to attempt to make changes in the attitude of a person about a particular thing or situation.
As a result, the person is ready to defenses up with regard to that idea of persuasion which Builds up defenses for the situation. Therefore, the effect of persuasion is reduced on the person.
Thus, Matty's strategy is not very effective; forewarning tends to reduce the effectiveness of an attitude change
Elements in the same period Question 7 options: A) form bonds with the same type of elements. B) have the same number of protons. C) have the same number of valence electrons. D) have the same principal quantum number.
D is the answer .. I have send u pic also
Color of the CuCl2 hydrate before heating:
hydrated cucl2 have blue-green colour
Usually scientists do not specialize and study one aspect of the
natural world, but will focus on many aspects to understand
why and how things happen.
TRUE
FALSE
list four quantum no. that defines energy state of the electron in hydrogen along with their possible values and explain their significance in terms of orbitals?
(True or false) Two or more atoms combine to form a molecule ____
Answer:
false tjytyjiy
Explanation:
cnruujrkyrryyrkkurk
what is meant by reaction element
Answer: A reaction element are those elements that can take part in a chemical reaction.
Explanation:
An element is made up of atoms that has the same atomic number. It is the basic material of which all matter is composed of. These elements cannot be broken down further into smaller substances by any chemical reaction. Each element has a unique number of protons in its atom. For example,
--> a hydrogen atom has 1 proton,
--> a Helium atom has 2 protons,
--> a Lithium atom has 3 protons, and
--> a carbon atom has 6 protons.
A chemical reaction on the other hand involves rearrangement of the constituent atoms of reactants to create different substances as products. The bonds between atoms are either broken or created to form new molecules. There are different types of chemical reaction which includes:
--> Decomposition reaction
--> Neutralization reaction
--> single displacement reaction and
--> combustion reaction.
I need help on this question asap!
You are in a lab and you use 11.50 g of Na(s) to react with Cl(g). Below is the reaction that happens from this.
Na + Cl2 → NaCl
Your percent yield is 95%. From this info what is the actual yield?
Answer:
27.79 g to the nearest hundredth.
Explanation:
2Na + Cl2 ---> 2NaCl
Using the molar masses , the theoretical yield is:
46 g of Na yields 46 + 35.5*2 g NaCl
46 g ---> 117 g NaCl so
11.5 g ----> 117 * 11.5 / 46 g NaCl
But, as the yield is 90%
the actual yield is 0.95 * 117 * 11.5 / 46
= 27.79 g.
What is the molecular geometry of a molecule made of two atoms that share one pair of electrons and have no lone electrons pairs?
trigonal pyramidal
linear
trigonal planar
bent
Answer:
linear
Explanation:
Actually I consulted various sources too and that was the most sought answer,I just decided to answer you before studying it too
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 Iodine did not show Tyndall effect . Explain reason. iii) How can you relate particle size to Tyndall effect?
The question requires a good knowledge of the meaning of Tyndall effect or scattering of light by false solutions in chemistry
The student observed a beam of visible light through mixture A because A exhibits Tyndall effect
Tincture of Iodine does not show Tyndall effect because its solution consists of particles less than 1 nanometer in solution.
A solution may be classified as a true solution or a false solution. A true solution consists of particles which are less than 1 nanometer in solution. A true solution does not scatter visible light.
A false solution, on the other hand consists of particles larger than 1 nanometer and does scatter visible light.
Starch in water is an example of a false solution or colloid hence it exhibits Tyndall effect. The scattering of visible light by a solution is known as Tyndall effect.
Tincture of iodine and sodium chloride in water are all true solutions hence they do not scatter visible light.
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The boiling points of diatomic halogens are compared in the table.
Boiling Points of Diatomic
Halogens
Molecule
Boiling Point
F2
-188 °C
Cl2
-34 °C
Br2
59 °C
12
184°C
Which of the following statements best explains the trends in boiling points?
The atomic size increases down the group, and this decreases the strength of the intermolecular forces.
The total number of electrons decreases down the group, and this decreases the strength of the intermolecular forces.
The total number of electrons increases down the group, and this increases the strength of the intermolecular forces.
The chances of forming a permanent dipole increases down the group, and this increases the strength of the intermolecular forces.
Which of the following statements best explains the trends in boiling points?
A. The atomic size increases down the group, and this decreases the strength of the intermolecular forces.
A is incorrect
B. The total number of electrons decreases down the group, and this decreases the strength of the intermolecular forces.
B is incorrect
C. The total number of electrons increases down the group, and this increases the strength of the intermolecular forces.
C is correct
D. The chances of forming a permanent dipole increases down the group, and this increases the strength of the intermolecular forces.
D is incorrect
The boiling point increase down a group because the total number of electrons increases down the group, and this increases the strength of the intermolecular forces. Hence option C is correct.
What is boiling point?Boiling point of a substance is the temperature at which the substance changes from its liquid state to vapour state. Boiling point of a molecule or compounds depends on the bond type, molecular weight, temperature and pressure.
For ionic compounds, boiling point will be higher since ionic bonds are stronger than covalent compounds. There is a periodic trend for the physical properties such as boiling point for elements in periodic table.
Down a group, the number of electrons increases and the atomic size also as well as the ionic character increases down a group . These two facts leads to higher intermolecular attraction, thus more temperature have to applied to weaken the bonds.
Higher temperature to be applied means the boiling point of the substance is higher. Therefore, boiling point down a group increases because of the higher intermolecular attraction as said in option C.
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(answered on edge)
Calculate the percent by mass of each element.
%N = 35 %
%H = 5.0 %
%O = 60 %
Answer:
N=35%. so 35/100*7 =2.45%
H=5.0 so 5/100*1=0.05%
o=60% so 60/100*8=4.8%
A compound was found to contain 90.6% lead (Pb) and 9.4% oxygen. What is the empirical formula for this compound?
Answer:
the answer is 47.9 and ik because I just had that question
The empirical formula of the compound is O₄Pb₃.
What is the empirical formula?
An Empirical system is the chemical system of a compound that offers the proportions of the elements gifted within the compound however not the real numbers or arrangement of atoms. This would be the lowest complete variety ratio of the elements within the compound.
Amount of lead (Pb) = 90.6%
⇒and amount of oxygen = 9.4%
taking the whole number ratio
o = 4
Pb = 3
∴ ⇒O: Pb=4:3
O4Pb3 answer.
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ASAP
Which of the following gases will have the highest rate of effusion at a given temperature?
Cl2
He
O2
Ne
Answer:
chlorine Will be at highest
A sample of helium has a temperature of 450 K. The gas is cooled to 248.9 K at which time the gas occupies 103.4 L? Assume pressure is constant at 3 atm. What was the original volume of the gas?
A. 186.94 L
B. 304.5 L
C. 57.19 L
D. 361.07 L
Answer:
[tex]\boxed {\boxed {\sf A. \ 186.94 \ L}}[/tex]
Explanation:
We are asked to find the original volume of a gas given a change in temperature. Since pressure remains constant, we are only concerned with volume and temperature, so we use Charles's Law. This states the volume of a gas is directly proportional to the temperature. The formula for this law is:
[tex]\frac {V_1}{T_1}= \frac{V_2}{T_2}[/tex]
The gas begins with a temperature of 450 Kelvin, but the volume is unknown.
[tex]\frac {V_1}{450 \ K }= \frac{V_2}{T_2}[/tex]
The gas is cooled to 248.9 Kelvin and the gas occupies a volume of 103.4 liters.
[tex]\frac {V_1}{450 \ K }= \frac{103.4 \ L}{248.9 \ K}[/tex]
Since we are solving for the original volume, we must isolate the variable V₁. It is being divided by 450 Kelvin. The inverse operation of division is multiplication, so we multiply both sides of the equation by 450 K.
[tex]450 \ K \frac {V_1}{450 \ K }= \frac{103.4 \ L}{248.9 \ K}* 450 \ K[/tex]
[tex]V_1= \frac{103.4 \ L}{248.9 \ K}* 450 \ K[/tex]
The units of Kelvin cancel.
[tex]V_1= \frac{103.4 \ L}{248.9 }* 450[/tex]
[tex]V_1= 0.4154278827 \ L *450[/tex]
[tex]V_1= 186.9425472 \ L[/tex]
Round to the nearest hundredth. The 2 in the thousandths place tells us to leave the 4 in the hundredth place.
[tex]V_1 \approx 186.94 \ L[/tex]
The original volume is approximately 186.94 liters and Choice A is correct.
hii pls help me to balance the equation and state the symbols thanksss
Explanation:
2Fe (s) + 3Cl2 (g) = 2FeCl3 (s)
3. What would be the freezing point for a 5.7 molal aqueous sucrose (C12H22O) solution? The freezing
point depression constant for water = 1.86°C/m. Show your work.
Answer:
- 10.6° C
Explanation:
Given that,
In the aqueous sucrose solution,
Molality of the solution (m) = 5.7
Freezing point constant (K) = 1.86
To find,
The freezing point of the solution = ?
Method:
To find its freezing point, we will first find out if the solute demonstrates an electrolyte or not.
In case it is not, the van't Hoff factor i.e. ration of particles' concentration denoted by (i) would be taken as 1. So,
ΔT(change in temperature) = i * m * K (putting the given values)
= 1 * 5.7 * 1.86
= 10.6° C
Thus, the freezing point equals to 0 - 10.6° C = -10.6° C.
write the electronic configuration of the first 20 element
what is the name of this organic molecule
Answer:
C2H4 Ethylene
Explanation:
Hope it helps! :)
Question 10 of 10 A certain seed is surrounded by a sticky coating. It is fairly dense and does not float in water. How is this seed most likely spread?
A. It is dispersed by the wind, and it sprouts after it falls to the ground
B. It drops to the bottom of a body of water, where it sprouts.
C. It attaches to the fur of an animal, and it sprouts after it falls from the animal's fur.
D. Animals eat it, and it is deposited in their waste.
What is the aim of cleaning of the iron nails before doing the experiment?
what is the reactant(s) in the chemical equation below
3CO(g) + Fe2O3(s) 2Fe(s) + 3CO2(g)
Answer:
the reactants are carbon dioxide ,iron, oxygen
what is true about solubility
Explanation:
Solubility is defined as a property of solutes by virtue of which they get dissolved in a favorable solvent. The solute can only be dissolved in any suitable solvent up to a limit at a given temperature. This is a characteristic of the the solute-solvent pairing.
