Find the expectation value 〈r〉 of r for an electron in the ground state of hydrogen. The normalized radial wave function for such an electron is 2a−3/2e−r/a , where a is the Bohr radius.Express your answer in terms of a

Answer:

flow

Explanation:

Answer:

Both liquid and gas particles can slide past one another, this is known as the ability to flow.

Answer:

no

Explanation:

For any given isotope, the sum of the numbers of protons and neutrons in the nucleus is called the mass number. This is because each proton and each neutron weigh one atomic mass unit . By adding together the number of protons and neutrons and multiplying by 1 , you can calculate the mass of the atom.

Answer:

No

Explanation:

An element's mass number (A) is the sum of the number of protons and the number of neutrons. Protons and neutrons both weigh about one atomic mass unit or amu. Isotopes of the same element will have the same atomic number but different mass numbers.

Answer:

Refer to the picture.

Answer: 16 Nm

Explanation: Work is measured as Force times Displacement . Therefore , 160N X 0.1m = 16 Nm

False

Atomic attributes are attributes that cannot be further divided. They are indivisible attributes that represent the smallest possible unit of information in a given context. For example, in a student record, the atomic attributes could be the student ID number, first name, last name, and date of birth.

In the context of database design, an attribute refers to a characteristic or property of an entity or object. Atomic attributes are those that are indivisible or cannot be further broken down into smaller components within the given context.

Atomicity is an important concept in database normalization, which is the process of organizing data in a database to eliminate redundancy and ensure data integrity. The first normal form (1NF) requires that each attribute in a relation (table) should hold only atomic values. This means that a single attribute should not contain multiple values or be composite in nature.

For example, let's consider a table representing employees in a company. The attribute "Name" would typically be atomic because it represents a single piece of information and cannot be further divided into smaller components within the given context. On the other hand, an attribute like "Address" might not be atomic since it can contain multiple elements such as street, city, state, and postal code.

By ensuring that attributes are atomic, it becomes easier to manipulate and query the data, maintain data consistency, and avoid data redundancy. It also helps in establishing a clear and well-defined structure for the database, making it easier to manage and analyze the data effectively.

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Answer:

A

Explanation:

Rock sand sun arent living.  cactus lizard sam and snake are living or biotic

The crystal system that exhibits the specified interaxial angle relationship is the hexagonal system.

The crystal system that has the following interaxial angle relationship is the hexagonal system. In the hexagonal system, the interaxial angle between any two crystallographic axes is 120 degrees, which is a characteristic feature of this system. The other crystal systems, including triclinic, tetragonal, orthorhombic, monoclinic, rhombohedral, and cubic, do not have a fixed interaxial angle relationship. Each of these systems has its own unique set of interaxial angles that define their crystal structures. Therefore, the interaxial angle relationship specified in the question specifically corresponds to the hexagonal crystal system.

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Answer:

basic

Explanation:

because H is hydrogen

Answer:

hehe you might think im crazy but this answer makes no sEnSe

Explanation:

Answer:

i think its a if not sorry i have it in a test right now

Explanation:

Catalysts, such as the minerals deposited on hydrothermal vent walls, bring reactants together and increase the speed of the reactions without providing energy.

We can define catalysts as substances that increase the speed of a reaction. The catalysts themselves remain unchanged in a chemical reaction and work by lowering the temperature, pressure and energy levels.

Without a catalyst, a chemical reaction will take a long time to occur.

The rate of a reaction increases using a catalyst for the reaction. Some of the minerals that act as catalyst in hydrothermal vents are iron, nickel and sulfide minerals.

The oxides of most metals acts as catalysts. Inside the body of organisms, enzymes act as biological catalysts.

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The possible causes of bedding in sedimentary rocks can include:

ii. Change in climate

iv. Discrete events

v. Change in sea level

vi. Change in sediment supply

vii. Change in currents

Layering in sedimentary rocks, as well as occasionally in metamorphic rocks, is known as bedding. Bedding can happen when a fresh layer of sediment is deposited on top of an older layer of sediment or when exposed sedimentary rock receives a new layer of sediments.

Since the bigger, older grains lie towards the base of the bed, bedding may be used to identify the oldest and youngest rocks in a sedimentary succession. One of the geologist's most crucial tools for understanding Earth's history is understanding the origin, make-up, and interpretation of bedding variation.

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Answer:

product

Explanation:

It is the right answer.

Answer:

Everyone, the answer is actually B. Providing shelter for marine organisms

Explanation:

We just went over this question in class, this is the right answer. Causing sediment to erode in the waters just doesn't make any sense.

The materials which are used to construct artificial reefs includes rocks, wood, old tires, etc. The artificial reef affect the ocean ecosystem by providing shelter for marine organisms. The correct option is B.

An artificial reef is defined as the manmade structure which may mimic some of the characteristics of the natural reef. The submerged shipwrecks are the most common form of artificial reef. The oil and gas platforms, bridges, etc. and other offshore structures are also function as artificial reefs.

From tourism to marine recreation and also for sport fishing, the reefs play an important role in local economies. They are also important for the health of the ocean and provides habitat for the variety of marine life and support the ocean ecosystems.

The artificial reefs are generally constructed to protect and enhance or restore the components of the marine ecosystems.

Thus the correct option is B.

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The false statement is applied pressure only refers to atmospheric pressure and the correct option is option 1.

It is the ratio of the force applied to the surface area over which the force is applied. Pressure can be defined as the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Atmospheric pressure is the pressure exerted by the atmosphere on the earth.

Thus applied pressure not only represents atmospheric pressure.

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Answer:

answer is b

Explanation:

I think it is b. I don't know what land lenses are but focusing light on the can would heat it up more.

\(E=hc/ \lambda\) is the equation for calculating the energy and wavelength of electron transitions in a one-electron system.

E = hv is the formula for calculating the energy of a single photon. It takes into account the energy in SI units of J, Planck's constant (h = 6.626 x 10-34 J s), and the frequency of the radiation in SI units of s-1 or Hertz, Hz. Wavelength and frequency are connected by the formula c/, where c is the speed of light, which is 2.998 x 108 m s-1.

The energy of the photon increases as the wavelength of light decreases. By dividing the aforementioned equation by Avogadro's number, one can determine the energy of a mole of photons with the wavelength

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Answer:

all of the above

Explanation:

Answer: All of the above

Explanation:

The Ag\(_{2}\)CO\(_{3}\)   is formed when 25.0 ml of 0.200M AgNO\(_{3}\) is mixed with 50.0 ml of 0.800 M Na\(_{2}\)CO\(_{3}\) is 0.68 g.

According the question , the chemical equation is give by :

2AgNO\(_{3}\)   +   Na\(_{2}\)CO\(_{3}\)  ------->   Ag\(_{2}\)CO\(_{3}\)     +      2NaNO\(_{3}\)

Given that :

volume of silver nitrate = 25.0 ml or 0.025 L

molarity M =  0.200 M

volume of sodium carbonate = 50.0 ml or 0.050 L

molarity = 0.800 M

now, no. of moles of silver nitrate  =  0.025 × 0.200 = 0.005 moles

no. of mole of sodium carbonate = 0.050 × 0.800 =  0.04 moles

the no. of moles of silver carbonate ,  =  0.5 × 0.005

                                                                =  0.0025 moles

molar mass  of Ag\(_{2}\)CO\(_{3}\) = 275.7 g/mol

therefor, the mass of Ag\(_{2}\)CO\(_{3}\) =   0.0025 moles × 275.7 g/mol

                                                 =0.68 g

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Answer:

These are compounds.

Explanation:

As it is formed by chemically bonding of two elements C ( carbon) and H (hydrogen) .

Answer:

Butane and benzene are both compounds. They contain multiple elements bonded together in a specific ratio. Kerosene and gasoline are mixtures because they are combinations of several compounds. Oxygen is an element because it is made up of only one type of atom.

Explanation:

7 moles of CH₄ are contained in 112 g of that substance.

One mole of a chemical is equal to 6.022 x 1023 molecules (or formula units) (ionic compound). A chemical's molar mass is equal to the mass of one mole of that substance. In other words, it provides you with the amount of grams per mole of a substance.

Atomic mass is the mass of a single compound unit, whereas molecular mass refers to the mass of a single mole of a compound. In essence, molar mass refers to the mass of a compound's average number of elements, whereas atomic mass refers to the mass of an individual atom.

Given mass = 112g

Molar mass of CH4 = ( 1 x 12 ) + ( 4 x 1) = 16 gmol-1

Number of moles = mass / Molar mass

Number of moles = 112 g / 16 gmol-1

Number of moles = 7 moles.

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Based on the information, UV light is more likely to damage the material.

Due to the fact that the infrared light bounces off the quartz, which increases its energy, the quartz may become warm.

The colors of paper and fabric can deteriorate due to ultraviolet light from the sun. In the presence of ultraviolet light waves, the chemicals in colored dyes can degrade. Sunburns may also result from ultraviolet radiation.

Paper and other organic materials will deteriorate, bleach, and deteriorate due to ultraviolet radiation. All of these modifications may reduce readability, affect how well artwork is regarded for its aesthetic qualities, and restrict access to the information it contains.

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Saturated solution means As much solute as possible is dissolved in the solvent.

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Element “X” belongs to family 2A, meaning it is part of the family that includes elements such as Be and Mg. These elements will all have 2 valence electrons and can be represented by the following Lewis diagram:

Element “Y” belongs to family 5A, meaning it is part of the family of elements that includes elements such as N and P. These elements will all have 5 valence electrons and can be represented by the following Lewis diagram:

Atoms from these two families will usually react with each other by losing or gaining valence electrons to create stable ions (an ion is what we call an atom/particle that has a charge). These stable ions form by the atoms either losing or gaining electrons until they have the same number of valence electrons as the nearest Noble Gas. This means that each ion will have a full valence shell (usually consisting of 8 electrons), often referred to as a “stable octet”, and this process of creating stable ions is often called the “octet rule”.

Atoms with fewer that 4 valence electrons will normally have a weak hold on their valence electrons and will tend to lose their valence electrons when forming ions.

Atoms with 4 or more valence electrons will normally have a strong hold on their valence electrons and will tend to gain electrons when forming ions.

The charge on the ion arises from the fact that, initially, the atom is electrically neutral because it has the same number of electrons (negative charges) as protons (positive charges). By losing electrons, the atom will end up with more protons (positive charges) than electrons (negative charges) and will form an ion with an overall positive charge. By gaining electrons, the atom will end up with more negative electrons than positive protons becoming an ion with an overall negative charge.

So, an atom of element “X”, with only 2 valence electrons, must lose its 2 valence electrons (which will be gained by element “Y”) to form a stable ion with a 2+ charge (losing two electrons leaves the ion with 2 more positive charges (protons) than negative charges, so a net charge of 2+).

An atom of element “Y”, with 5 valence electrons, must gain 3 electrons (from element “X”) to form a stable ion with a 3- charge (gains 3 extra negative charges).

We can show this process using Lewis diagrams:

From this set of diagrams you can see that in order to create stable ions of both “X” and “Y” we need these atoms to react with each other in a 3:2 ratio (we need 3 atoms of X for every 2 atoms of Y). This means that the resulting chemical formula of the compound will be:

Now, we will look at a short cut that can help you figure this out without having to draw Lewis diagrams.

Compounds are electrically neutral, meaning they must contain equal numbers of positive and negative charges. For compounds consisting of oppositely charged ions, this means that the total charge of the negative ions must be equal to the total charge of the positive ions. In other words the ions must combine in a ratio that makes their charges add to zero.

If we look at the compound we just made, X3Y2, we can confirm this:

So, now you can you predict the formula of simple ionic compounds:

from the family of elements, determine the number of valence electrons each element has

determine the charge of the ions that each atom will form using the octet rule (or look on the periodic table, most will tell you the stable ionic charges that each element can form)

determine the ratio of positive ions to negative ions that results in an overall charge of zero

Example,

What is the formula of a compound produced when an element from family 3A combines with an element from family 7A?

The formula of sodium hydrogen phosphate is Na₂HPO₄.

3.2 moles of Na₂HPO₄ contains 6.40 moles of Sodium atoms.

Two mole of sodium, one moles of hydrogen, one mole of phosphate, and four moles of oxygen make up one mole of sodium hydrogen phosphate, or Na₂HPO₄.

Given;

1 mole of Na₂HPO₄ contains 2 moles of Sodium  

3.2 moles of Na₂HPO₄ will contain =?

= 3.2 moles x 2  

= 6.40 moles  

Therefore;  

3.2 moles of Na₂HPO₄ contains 6.40 moles of Sodium atoms.

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The molality of the sugar solution is 0.262 mol/kg.

To find the molality of the sugar solution, we need to first calculate the moles of sugar and the mass of solvent (water) in kilograms:

Moles of sugar = Mass of sugar / Molecular weight of sugar

Moles of sugar = 146.739 g / 110 g/mol

Moles of sugar = 1.333 mol

Mass of solvent (water) = Volume of solution - Mass of solute (sugar)

Mass of solvent (water) = 5.23 L - 0.146739 kg (since density of water is approximately 1 kg/L)

Now we can calculate the molality:

Molality = Moles of solute / Mass of solvent (in kg)

Molality = 1.333 mol / 5.083261 kg

Molality = 0.262 mol/kg

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The hydronium ion concentration, [H₃O⁺ ], of the solution is  3.83 * 10⁻⁶.

The hydronium ion concentration of a solution is the concentration in mol/dm³ of the hydronium ions of a solution.

The hydronium ion is formed when a water molecule combines with a hydrogen ion as shown below:

H₂O + H⁺ ---> H₃O⁺

The hydronium ion concentration of a solution is also known as the hydrogen ion concentration of the solution or pH.

The product of the hydronium ion concentration of a solution and the hydroxide ion concentration of a solution gives the ion product of water.

[H₃O⁺ ] * [OH⁻] = Kw

where Kw = 1.0 * 10⁻¹⁴ M²

The hydronium ion concentration of the given solution can be calculated as follows:

[H₃O⁺ ] * [OH⁻] = Kw

[OH⁻] = 2.61 * 10⁻⁹ M

Kw = 1.0 * 10⁻¹⁴ M²

[H₃O⁺ ] = Kw / [OH⁻]

[H₃O⁺ ] = 1.0 * 10⁻¹⁴ M² / 2.61 * 10⁻⁹ M

[H₃O⁺ ] = 3.83 * 10⁻⁶

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