What is indicated by 'A' in the figure below? A. -VE B. +Ea C. -Ea D. +VE

Answer:

Force=mass ×acceleration.

20=10×acceleration.

20=10a.

a=2m/s^2.

Answer:

Cells are the "building blocks for all living things." Without cells, we couldn't survive. Cells do many important things. Some of the things they can do are taking in food nutrients, frame our bodies, and change the food nutrients into energy.

Answer:

4.30 × 10²⁰ atoms

Explanation:

You need to find out how many moles you have.  First, convert milligrams to grams.

62.5 mg × (1 g)/(1000 mg) = 0.0625 g

Next, use the molar mass to convert from grams to moles.

0.0625 g ÷ 87.62 g/mol = 7.13 × 10⁻⁴ mol

To convert from moles to atoms, you need to use Avogadro's number (6.022 × 10²³).  Avogadro's number is the number of atoms in a mole.

7.13 × 10⁻⁴ mol × 6.022 × 10²³ atoms/mol = 4.296 × 10²⁰ ≈ 4.30 × 10²⁰ atoms

You will have 4.30 × 10²⁰ atoms of strontium.

The number of Strontium atoms are 4.30 × 10²⁰ atoms

Given:

Mass of Strontium = 62.5 mg × (1 g)/(1000 mg) = 0.0625 g

Molar mass of Strontium = 87.62 g/mol

To find:

Moles of Strontium = ?

It is defined as given mass over molar mass.

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}\\\\\text{Number of moles}=\frac{0.0625 g}{87.62 g/mol }\\\\\text{Number of moles}=7.13 * 10^{-4} mol[/tex]

Avogadro's number is the number of atoms in a mole (6.022 * 10²³)

Conversion of moles into atoms:

[tex]7.13 × 10^{-4} mol * 6.022 * 10^{23} atoms/mol \\\\\text{ Sr atoms}= 4.296 * 10^{20} = 4.30 * 10^{20} atoms[/tex]

Thus, Strontium atoms will be 4.30 × 10²⁰ atoms.

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Answer: Air and fuel intake, compression and ignition, combustion and expansion, exhaust

Explanation:

Explanation:

ionic compounds have high melting points

Answer is D

Explanation:

Answer:

B. Neutral

Explanation:

When there is a ionic bond,  one element steals or takes away an electron from the other element.

An example is NaCl

In this compound, Chlorine atom steals an extra electron from Sodium to fill its outer shell. So, this is a Ionic bond. Since, the Sodium compound gives away an atom, it is positively charged. Since, Chlorine steals an atom, it is negatively charged. Opposite charges attract, so they become a compound.

When positive and negative mix, it becomes neutral.

The transformation of liquid into solid when it reaches when it's temperature is below freezing point.

Answer:

Freezing:

When liquid is converted to solid, the process is called freezing.

Conditions for freezing:

1) Temperature must be lowered.

2) The temperature should be below 0 degree centigrade.

Example:

The conversion of "liquid water" into "ice".

=> We can use a "freezer" to freeze things.

It causes freezing point depression which requires the gasoline to reach a much lower temperature before freezing. Hence, option C is correct.

Whenever a solute is added to a solution/solvent, it leads to depression in the freezing point of that solution/solvent. Depression in the freezing point of a solution on the addition of a solute is a colligative property.

A colligative property is a physical property which depends upon the number of solutes added not on the nature of solutes which means it does not matter whether we are adding 1000 particles of sugar or salt in water, the depression in the freezing point will occur by the same °C. Also, the more a solute is added the more will be the depression at the freezing point.

The formula for depression at the freezing point is mentioned as under:

             Δ T = K x m

where Δ T = freezing point depression;

                 K = cryoscopic constant;

                 m = molality of the solution.

For example, The freezing point of water is 0 °C but as soon as we add a 92 gm solute like NaCl (common salt) in 1000 gm of water, its freezing point will be lower to −3.72 °C.

Hence, option C is correct.

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Answer:

[tex]\large \boxed{350}[/tex]

Explanation:

In multiplication and division problems, the answer can have no more significant figures than the number with the fewest significant figures.

My calculator gives the result:

[tex]\dfrac{4568}{13} = 351.3846154[/tex]

4658 has four significant figures.

     13 has two significant figures.

You must round to two significant figures.

That is, you drop all the digits to the right of the 5 — the red line in Fig. 1 below. You are rounding to the nearest ten.

To round a number to the nearest ten, you look at the number in the ones place (1). See Fig. 2.

If the number to be dropped — the digit in the ones place — is less than 5, you drop the digit in the ones place (Fig. 3). It becomes a zero.

The number in the tens place is a trailing zero. It is not significant.

[tex]\text{The quotient of $\dfrac{4658}{13}$ is $\large \boxed{\mathbf{350}}$}[/tex]

Answer:

Halogens

Explanation:

Matter is defined as a substance which has mass and occupies volume. The three states of matter are solid, liquid and gas.

Elements which are present in group 17 are known as halogens.

Elements present in this group are fluorine, chlorine, bromine and iodine.

At room temperature, both fluorine and chlorine exists as a gas.

Bromine exists as a liquid and iodine exists as a solid.

Therefore, we can conclude that halogen groups are likely to have elements in three states of matter.

Answer:

Iodine

Explanation:

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Answer:

The scientists and all test subjects involved in the investigation work for the company that sells the medication.

Explanation:

The options are as below:

A. The investigation compared a group that took the medication to a control group that did not take the medication.

B. The scientists and all test subjects involved in the investigation work for the company that sells the medication.

C. The weight loss medication worked for 95 out of the 100 test subjects, while only 15 of the 100 control subjects lost weight.

D. The weight loss results were replicated by scientists conducting a study at an independent institution

The correct option would be that the scientists and all test subjects involved in the investigation work for the company that sells the medication.

When selecting the test subjects for research, the selection must be as random as possible so as to ensure an unbiased outcome and increase the reliability of the research.

Limiting the test subjects to those that work in the company that sells the medication will generally reduce the reliability of the outcome because of element of bias that can be introduced either knowingly or unknowingly.

The test subjects must have been selected from the general population of target users for the medication and not limited to just the employees of the manufacturing company.

Correct option: B

Answer:

[tex]\large \boxed{\text{183 g}}[/tex]  

Explanation:

[tex]\begin{array}{rcl}\text{Density} & = & \dfrac{\text{Mass}}{\text{Volume}}\\\\\rho & = &\dfrac{m}{V}\\\\1.83 \text{ g$\cdot$ cm}^{-3} & = & \dfrac{m}{\text{100 cm}^{3}}\\\\m & = & \text{183 g}\\\end{array}\\\text{There are $\large \boxed{\textbf{183 g}}$ of sulfuric acid.}[/tex]

Answer:

[tex]7.589\times 10^{2}[/tex]

Explanation:

The expression can be solved mathematically as follows:

1) [tex]8.310\times 10^{2}-7.210\times 10^{1}[/tex] Given

2) [tex]8.310\times 10^{1+1} - 7.210\times 10^{1}[/tex] Definition of sum

3) [tex](8.310\times 10^{1})\times 10^{1}-7.210\times 10^{1}[/tex] [tex]a^{m+n} = a^{m}\cdot a^{n}[/tex]/Associative property

4) [tex](8.310\times 10^{1}-7.210)\times 10^{1}[/tex] Distributive property

5) [tex](83.100-7.210)\times 10^{1}[/tex] Multiplication

6) [tex]75.89\times 10^{1}[/tex] Subtraction.

7) [tex](7.589\times 10^{1})\times 10^{1}[/tex] Multiplication/Associative property

8) [tex]7.589\times (10^{1}\times 10^{1})[/tex] Associative property

9) [tex]7.589\times 10^{2}[/tex] [tex]a^{m+n} = a^{m}\cdot a^{n}[/tex]/Result

Answer:

20 mL

Explanation:

The student should record 20 mL as the correct volume.

The curved surface of a liquid that is usually observed in a buret is referred to as the meniscus. This meniscus is created as a result of the surface tension of the liquid against the walls of the buret. Hence, in order to avoid errors due to parallax, the bottom of the meniscus should be read and not the top.

Therefore, the correct volume that the student should record is 20 mL.

Answer:

Chlorine has strong inter molecular forces than iodine

Explanation:

Answer:

Chlorine has strong inter molecular forces than iodine

Explanation:

I2 is a solid while Cl2 is a gas because Iodine molecules are larger and therefore experience stronger intermolecular forces.

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Answer: Johannes Kepler

Answer:

i believe the answer us kepler

Explanation:

Answer:

Iron and aluminum are both examples of metals that are used commonly in everyday life.

Answer:

Distance.

Explanation:

Wavelength (λ) can be defined as the distance between two successive crest or trough of a wave.

From the above definition, wavelength (λ) simply measures distance.

This can further be explained by obtaining the unit of measurement for wavelength (λ).

This can be illustrated below:

Wavelength is related velocity and frequency according to the following equation:

Velocity (v) = wavelength (λ) x frequency (f)

v = λf

λ = v/f

Velocity is measured in ms¯¹

Frequency is measured in hertz, Hz (s¯¹)

λ = v/f

λ = ms¯¹ / s¯¹

λ = m

We can see that wavelength is measured in metre (m) which is the same unit for measuring distance.

Therefore, wavelength measures distance.

Answer:

The answer is D.

Explanation:

Malleable is the property of metal not non-metal.

Answer:

malleable

Explanation:

An atom Y has atomic number 13, so the no. of electrons and protons in it is 13 and after loses it will form cation and no. of electrons will become 10.

Atomic number of an atom is equal to the number of electrons or protons present in that atom.

Number of protons and electrons in the atom before loses electron is 13, as given atomic number is 13.

Number of elctrons in the atom is 10 and number of protons is 13, as protons are present in the nucleus.

So, number of protons is always same i.e. 13 within the atom and no. of electrons after losing 3 electrons is 10.

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Answer:

Alpha decay is a type of radioactive disintegration in which unstable atomic nucleus releases a helium nucleus or alpha particle and transform into a different element. The new element formed will be reduced by four and the atomic number will be reduced by two.

Example of alpha decay is: Uranium 238 transform into Thorium 234 with the emission of an alpha particle.

Answer:

iii. 3 moles of A react with 2 moles of B to form 1 mole of A 3B 2

Explanation:

A + 2 B → A 3B 2

A chemical equation among other things, gives the stoichiometry of the reaction; that is the relationship between reactants and products.

This relationship is basically stated in moles form the coefficients of the reactants and product.

From the reaction above, we can say;

1 mol of A reacts with 2 mol of B to form 1 mol of A3B2

It cannot be grams because the reactants and products all have different molar masses.

The correct interpretation of the equation of the hypothetical chemical reaction is; Choice (iii) 3 moles of A react with 2 moles of B to form 1 mole of A 3B 2.

Definition:

Chemical equations are equations that make use of chemical formulae and symbols to represent chemical reactions. The left-hand side of a chemical equation represents the reactants and the right-hand side represents the products.

Each reacting entity is also assigned its corresponding stoichiometric coefficient.

However, this stoichiometric coefficient is to quantify the no. of moles of the reactants consumed or products formed as the case may be.

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Answer:

Wavelength (λ) = 1.875 × 10⁻⁶ m

Explanation:

Given:

Energy (e) =  1.06 × 10⁻¹⁹ J

Find:

Wavelength (λ) = ?

Computation:

e = hc / λ

λ = hc / e

where c = 3 × 10⁸

Planck's constant (h) = 6.625 × 10⁻³⁴

So,

Wavelength (λ) = (6.625 × 10⁻³⁴)(3 × 10⁸) / (1.06 × 10⁻¹⁹)

1. Wavelength (λ) = 1.875 × 10⁻⁶ m

2. Given n = 4 to n = 3 both are integer not fraction so, electron is quantize

Answer:

Reduce high-pressure gas in the scuba cylinder to ambient (surrounding) pressure.

Explanation:

The primary function of a scuba regulator would be to reduce high-pressure gas in the scuba cylinder to ambient pressure.

A scuba regulator is a structure found attached to the scuba cylinder usually carried by scuba divers. The structure regulates the pressure of the breathing gas in the cylinder to a safe level before the gas becomes available for the breathing process of divers.

Usually, the gas in a scuba cylinder is at a high level. Hence, what the regulator does is to bring it down to a level that would be safe for the breathing of the diver.

Answer:

C. 1 cubic foot of loose sand

Explanation:

For many  objects having equal volume , surface area will be maximum

of the object which has spherical shape .

But when a sphere is broken into tiny small spheres , total surface area of all the small spheres will be more than surface area of big sphere .

Hence among the given option , surface area of loose sand will have greatest surface area . Loose sand is equivalent to small spheres .

Answer:

the answer would be C 1 cubic foot of loose sand.

Answer:

No

Explanation:

Droplets or aerosols. When an infected person coughs, sneezes, or talks, droplets or tiny particles called aerosols carry the virus into the air from their nose or mouth. Anyone who is within 6 feet of that person can breathe it into their lungs.

Airborne transmission. Research shows that the virus can live in the air for up to 3 hours. It can get into your lungs if someone who has it breathes out and you breathe that air in.

Surface transmission. Another way to catch the new coronavirus is when you touch surfaces that someone who has the virus has coughed or sneezed on. You may touch a countertop or doorknob that's contaminated and then touch your nose, mouth, or eyes. The virus can live on surfaces like plastic and stainless steel for 2 to 3 days. To stop it, clean and disinfect all counters, knobs, and other surfaces you and your family touch several times a day.

Fecal-oral. Studies also suggest that virus particles can be found in infected people's poop. But experts aren't sure whether the infection can spread through contact with an infected person's stool. If that person uses the bathroom and doesn't wash their hands, they could infect things and people that they touch.

Answer:

Noble gases are the least reactive of all known elements. Their outer energy levels are full because they each have eight valence electrons. ... As a result, noble gases cannot become more stable by reacting with other elements and gaining or losing valence electrons.

Explanation:

Noble gases have complete valence shells so they do not participate in the reactions while the other elements in the main group have incomplete valence shells so they participate in the reaction to complete it.

Noble gases can be described as the six elements that belong to the 18th  group of the modern periodic table. The elements of group 18 are Helium, Neon, Argon, Krypton, Xenon, and Radon.

Under normal temperature and pressure conditions, all noble gases exist in the gaseous state and exhibit low chemical reactivity hence they are also referred to as inert gas.  All noble gases possess stable electronic configurations because their valence shell is fully filled.

Noble gases are generally found as mono-atomic gases. The general electronic configuration group 18 elements can be written as ‘ns²np⁶’ where n is the principal quantum number.

Therefore, the reactivity of the noble gases can be distinguished from other elements in the main group.

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Answer:

The scientific method is applied to inference through the steps taken to make both inductive and deductive inferences. Inductive inference begins with an observation, and then a pattern of such observation develops. One then makes a hypothesis based on the pattern and finally a theory based on the hypothesis

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