salks vaccine trail was a double-blind experiment true or false

Answer:

C.

Explanation:

The correct name of the compound whose chemical formula is Na₂SO₄ is sodium sulfate.

Chemical  formula is a way of representing the number of atoms present in a compound or molecule.It is written with the help of symbols  of elements. It also makes use of brackets and subscripts.

Subscripts are used to denote number of atoms of each element and brackets indicate presence of group of atoms. Chemical formula does not contain words. Chemical formula in the simplest form  is called empirical formula.

It is not the same as structural formula and does not have any information regarding structure.It does not provide any information regarding structure of molecule as obtained in structural formula.

There are four types of chemical formula:

1)empirical formula

2) structural formula

3)condensed formula

4)molecular formula

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Answer:

DO I Look Like santa too you how am i supposed to know How about this how about you goo.gle the answer wow smart

Explanation:

Answer:

It only has 7 valence electrons because there are seven electrons in the highest orbital.

Explanation:

Answer:

solar energy

Explanation:

Answer:

weathering

Explanation:

hope this helps

Answer:

ooooooooooooooooooh i dont know this one

Explanation:

im not good a math at all

Answer: The four seasons happen because of the tilt of the Earth's axis. At different times of the year, the sun's rays hit different parts of the globe more directly. The angle of the Earth's axis tilts the Northern Hemisphere towards the sun during the summer.

Explanation: I am not gonna tell u what exactly to pick but this should give an idea okai? Hope I can help u :)

Answer:

so whats the answer?

Explanation:

Answer:

a) single replacment........................

Answer:

It is 34

Explanation:

The atom that has 24 protons, 22 electrons, and 28 neutrons has an atomic number of 24.

ATOMIC NUMBER:

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Answer:

Greenhouse effect

Explanation:

Answer: water vapor, carbon dioxide and other gases absorb and reradiate thermal energy.

Explanation:

Answer:

2.34 moles

Explanation:

Given that,

Given mass = 16.3 grams

We know that, molar mass of lithium is 6.941 g/mol

Let there are n number of moles. It is given by :

n = given mass/molar mass

[tex]n=\dfrac{16.3\ g}{6.941\ g/mol}\\\\=2.34\ moles[/tex]

So, there are 2.34 moles in 16.3 grams of lithium

Answer:

its D.

Explanation:

Answer:

It's B

Explanation:

The classic rainbow is made of certain colors, so If a white light passed through a glass prism [and only glass] the rainbow would show because of the colors bending [the naked eye can't see that 0-0]

Also, you know the sky is blue right??  The color blue in that prism when the light shined over was the shortest and wavy color. each color has it's own wave. blue is just the shortest and waviest one.

Answer: im pretty sure its the last (one daughter cell has no similarity to its parent cell.)

Explanation: bc a daughter cell has 30 and the parent cell would have 46 and thats not twice or half as many and they arent the same either so the last one makes sences  

Answer:

A. 2Fe + 3Cl2 --> 2FeCl3

B. 2Fe + 3O2 --> 2Fe2O3

C. C4H10O + 4O2 --> 4CO2 + 5H2O

D. C7H16 + 11O2 --> 7CO2 + 8H2O

Explanation:

Answer:

Explanation:

The acceleration of an object given it's mass and the force acting on it can be found by using the formula

[tex]a = \frac{f}{m} \\ [/tex]

f is the force

m is the mass

From the question we have

[tex]a = \frac{120}{12} \\ [/tex]

We have the final answer as

Hope this helps you

Answer:

Josh is running at a speed of 9.09 yards per second.

Josh's velocity is 9.09 East.

Josh's force is 900 N.

Aaron Donald's force is 845 N.

Yes Josh scores the touchdown because he is faster and has more mass than Donald.

Explanation:

Josh scores the touchdown as he is heavier and faster than Donald.

Formulas are:

Force= mass x acceleration

Speed= distance divided by time.

Velocity= distance divided by time.

Answer:

In a physical change the appearance or form of the matter changes but the kind of matter in the substance does not. However in a chemical change, the kind of matter changes and at least one new substance with new properties is formed. The distinction between physical and chemical change is not clear cut.

Explanation:

Answer:

ive learned about the chart , ive learned about the coolest chemicle reactions and how. the can change colors , ive also learned that chenistrey is all around us since the beginning of life ,and how liquid can turn solid

Explanation:

Answer: The final volume of the balloon is 335.6 L

Explanation:

To calculate the final volume of the balloon, we use the equation given by combined gas law:

[tex]\frac{P_1V_1}{T_1}=\frac{P_2V_2}{T_2}[/tex]

where,

[tex]P_1[/tex] = Initial pressure = 1.2 atm

[tex]P_2[/tex] = Final pressure = [tex]3.00\times 10^{-3}[/tex] atm

[tex]V_1[/tex] = Initial volume = 1.00 L

[tex]V_2[/tex] = Final volume = ?

[tex]T_1[/tex] = Initial temperature = [tex]25^oC=[25+273]=298K[/tex]

[tex]T_2[/tex] = Final temperature = [tex]-23^oC=[-23+273]=250K[/tex]

Putting values in above equation, we get:

[tex]\frac{1.2atm\times 1.00L}{298K}=\frac{3.00\times 10^{-3}atm\times V_2}{250K}\\\\V_2=\frac{1.2\times 1.00\times 250}{298\times 3.00\times 10^{-3}}\\\\V_2=335.6L[/tex]

Hence, the final volume of the balloon is 335.6 L

Answer:

Because the intermolecular interactions are weaker.

Explanation:

Nonpolar substances do not have dipole-dipole or hydrogen bond interactions, which are strong intermolecular interactions that often make the substance liquid or solid. Instead, they must rely on van der Waals forces, which are relatively weaker interactions that are often insufficient to hold the molecules together in liquid or solid form.

The magnitude of intermolecular association in nonpolar substance is much lower than the magnitude of intermolecular association in polar substances.

Polar substances are those substances in which a permanent dipole exists in the molecule. In a molecule having a permanent dipole, the electronegativity difference between the atoms bonded in the molecule is high.

As a result of this high electronegtivity difference between atoms, the molecules interact more intimately hence polar molecules tend to exist mostly as liquids and gases while nonpolar molecules having less intimate intermolecular interaction via dispersion forces exist mostly as gases.

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Answer:It is a nuclear process, where energy is produced by smashing together light atoms. It is the opposite reaction of fission, where heavy isotopes are split apart.

Explanation Fusion is the process by which the sun and other stars generate light and heat.

It’s most easily achieved on Earth by combining two isotopes of hydrogen: deuterium and tritium. Hydrogen is the lightest of all the elements, being made up of a single proton and a electron. Deuterium has an extra neutron in its nucleus; it can replace one of the hydrogen atoms in H20 to make what is called “heavy water.”

Answer:

Explanation:

While trying to write the chemical formula for a compound (a neutral molecule), one must identify and exchange the charge of the cation with that of the anion to become the subscript of one other. For example

Aluminium oxide has Aluminium (Al) and oxygen (O); since Al has a charge of 3+ (the cation) and O has a charge of 2- (the anion), the compound would have it's charges as Al³⁺O²⁻ and when the charges are exchanged to there subscripts, it would form Al₂O₃; thus there would be two cations of aluminium for every three anions of oxygen in order to have a neutral molecule.

This same explanation can be given to Aluminium sulfite. Aluminium sulfite has Aluminium (Al) and sulfite (SO₃). Al has a charge of 3+ (cation) while sulfite has a charge of 2- (anion), with the compound having it's charges as Al³⁺(SO₃)²⁻ and when the charges are exchanged to there subscripts, it would form Al₂(SO₃)₃ and would thus have 2 cations of aluminium (Al³⁺) for every 3 anions of sulfite (SO₃³⁻) in order to have a neutral molecule.

Answer:

P(total) = 164 mmHg

Explanation:

Given data:

Partial pressure of helium = 77 mmHg

Partial pressure of nitrogen = 87 mmHg

Total pressure of flask = ?

Solution:

According to Dalton law of partial pressure,

The total pressure inside container is equal to the sum of partial pressures of individual gases present in container.

Mathematical expression:

P(total) = P₁ + P₂ + P₃+ ............+Pₙ

Now we will solve this  problem by using this law.

P(total) = P(He) + P(N₂)

P(total) =  77 mmHg + 87 mmHg

P(total) = 164 mmHg

Answer:

21.3dm³

Explanation:

Given parameters:

Initial volume of gas = 3dm³

Initial pressure  = 101kPa

Final pressure  = 14.2kPa

Unknown

Final volume  = ?

Solution:

To solve this problem, we use the Boyle's law which states that "the volume of a fixed mass of a gas varies inversely as the pressure changes if the temperature is constant".

Mathematically;

                P₁ V₁  = P₂ V₂

P and V are pressure and Volume

1 and 2 are the initial and final states

Now insert the parameters and solve;

         101 x 3 = 14.2 x V₂  

                  V₂  = 21.3dm³

Mass NF₃ at STP : 50.06 g

Conditions at T 0 ° C and P 1 atm are stated by STP (Standard Temperature and Pressure). At STP, Vm is 22.4 liters/mol.

15.8 L at STP, mol NF₃ :

[tex]\tt \dfrac{15.8}{22.4}=0.705[/tex]

mass NF₃ (MW=71 g/mol) :

[tex]\tt mass=mol\times MW\\\\mass=0.705\times 71\\\\mass=50.06~g[/tex]

Answer: Bismuth (Bi) , Nitrogen family

Explanation:

As the element has 5 valence electrons in the sixth energy level, which mens it belongs to 6th period as the valence electron has entered the 6th energy level.

Now as the electrons are  filled according to afbau's rule , the electronic configuration of the element will be :

[tex][Xe]4f^{14}5d^{10}6s^26p^3[/tex]

Now as the atomic number of element is equal to the number of electrons in a neutral atom , the atomic number is 83 and the element is Bismuth (Bi). As the last electron enters p -subshell , it is  a p block element. It lies in group 15 which is nitrogen family.

Answer:

runoff is he draining away of water (or substances carried in it) from the surface of an area of land, a building or structure, etc.

Explanation: