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

Answers

Answer 1

Answer:

true

Explanation:


Related Questions

What is the correct name for the compound whose formula is Na2SO4?
A
disodium sulfate
В.
sodium sulfoxide
С.
sodium sulfate
D
sodium sulfite

Answers

Answer:

C.

Explanation:

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

What is chemical formula?

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

Learn more about chemical formula,here:

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#SPJ6

The __________________ is the process by which gases in the atmosphere absorb and reradiate heat.

Answers

Answer:

Greenhouse effect

Explanation:

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

Explanation:

Why do nonpolar substances tend to be gases and not liquids or solids?

Answers

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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3
5) An atom has 24 protons, 22 electrons, and 28 neutrons. What is the
ATOMIC # of the atom?*
O 24
022
52
46

Answers

Answer:

It is 34

Explanation:

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

ATOMIC NUMBER:

The atom of an element is made up of three subatomic particles namely: neutron, proton and electron.

Proton is the positively charged component while electron is the negatively charged component.

The number of protons in the atom of an element represents the atomic number of that element.

Therefore, if an atom has 24 protons, 22 electrons, and 28 neutrons has an atomic number of 24.

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on 100 corex
c с

A flask contains helium and nitrogen
gases. The partial pressures of each are
77 mm Hg and 87 mm Hg, respectively.
Help Resources
What is the total pressure in the flask mm Hg

Answers

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

What type of reaction is this?

Zn + K2 CrO 4 --> K + ZnCro4

A) single replacement
B) double replacement
C) decomposition
D) synthesis

Answers

Answer:

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

In a short paragraph, explain one thing you've learned from the course this year.

Answers

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:

In mitosis, how does a daughter cell compare with its parent cell?
A.
A daughter cell has twice as many chromosomes as its parent cell.
B.
A daughter cell has half as many chromosomes as its parent cell.
C.
A daughter cell and its parent cell are exact copies of each other.
D.
A daughter cell has no similarity to its parent cell.

Answers

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  

When light pases through a prisim,white light will be separated into different colors. which statment best explains this observation?​

Answers

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.

Which of the following is NOT an ionic compound?
A. Carbon Dioxide
B. Lithium Oxide
C. Barium Oxide
D. Calcium Chloride

Answers

A. Carbon Dioxide, CO2 it’s a covalent bond.
A carbon dioxide okkk I have done this before

Someone please help will mark as brainliest

Answers

Answer:

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

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

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

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

Explanation:

Provide your answer in the following format: [element name], [chemical family]

Answers

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.

15.8 liters NF3 (at STP) converted to grams

Answers

Mass NF₃ at STP : 50.06 g

Further explanation

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]

PPLLLSSSSSSS HELLLPPP!!!!! What is runoff?

Answers

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:

look up the definition on the internet

How many valence electrons does this atom have? (Urgent)

Answers

Answer:

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

Explanation:

I need help please and thank you

Answers

Answer:

ooooooooooooooooooh i dont know this one

Explanation:

im not good a math at all

What type of energy is transmitted from the Sun to Earth through space?

Answers

Answer:

solar energy

Explanation:

Which process describes the wearing
away of rock?
A. drainage
B. erosion
C. infiltration
D. weathering

Answers

Answer:

weathering

Explanation:

hope this helps

LOTS OF POINTS (75) I WILL GIVE BRAINLIEST!!!!!

Whats the Difference between a chemical and physical change

Answers

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:

Which of the following would cause the seasons on Earth to change more gradually?
A Increasing the amount of time it takes Earth to orbit the Sun.
B Increasing the number of times Earth rotates on its axis per year.
C Decreasing the speed of the Moon’s orbit around Earth.
D Decreasing the amount of energy the Sun emits per year.

Answers

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:

how many moles are 16.3 grams of lithium

Answers

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

How much work is required to pull a sled if you use 60J of work in 5 seconds?

Answers

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:

What is a way in which nuclear fusion is used?

Answers

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.”

Las Vegas Raiders' running back Josh Jacobs is 72 inches tall and has mass of 100 kg. Los
Angeles Rams' defensive tackle Aaron Donald is also 72 inches tall but has a mass of 130
kg. Josh runs the ball East, towards the goal line, quickly traveling 50 yards in
5.5 seconds. Josh then accelerates towards the goal line at 9 m/s2. Aaron accelerates
West, the exact opposite direction, towards Josh at 6.5 m/s2. They both meet with an
explosive collision at the 1 yard line.
In a paragraph, address the following questions. Calculate numerical answers to the
nearest hundredth and correct units must be included.
1. What is Josh Jacobs' speed?
II. What is Josh Jacobs' velocity?
III. How much force does Josh Jacobs create?
IV. How much force does Aaron Donald create?
V. By calculating the net force, does Josh Jacobs score the touchdown.
Explain why or why not?

Answers

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.

The mixture of sodium bicarbonate (a base) with nitric acid (an acid) produces a salt and water. This type of reaction is known as which of the following?

A: oxidation-reduction
B: neutralization
C: single replacement
D: synthesis

Answers

Neutralization I think

A 12 kg object experiences a net force of 120 N. What acceleration will this object experience?

Answers

Answer:

10 m/s²

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

10 m/s²

Hope this helps you

A gas-filled balloon having a volume of 1.00 L at 1.2 atm and 25°C is allowed to rise to the stratosphere (about 30 km above the surface of Earth), where the temperature and pressure are -23°C and 3.00 10-3 atm, respectively. Calculate the final volume of the balloon.

Answers

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

URENT URENT URENT HELP PLEASE

Answers

Answer:

its D.

Explanation:

A gas sample has volume 3.00 dm3 at 101
kPa. What will be the volume if the
pressure is reduced to 14.2 kPa?

Answers

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

The chemical formula for the ionic compound aluminum sulfite is Al2(SO3)3. Explain why there are 2 cations for every 3 anions in this compound.

Answers

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.

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