Please help with number 7 thank you! 30 points

Answer:

2.00g/ml

Explanation:

If water has a density of 1.00g/ml, and theres

40ml of it, it would weigh 40g

The substance is twice as dense as water, making its density 2.00g/ml

Answer:

179.05 g/mol

Explanation:

simple called the percentage of the molecular mass of each isotope and add them together. their sum is the mass of Halfnium.

thus

Hf --- 74/100 × 180 = 133.2

Hf --- 17/100 × 176 = 29.92

Hf --- 9/100 × 177 = 15.93

total mass = 133.2+29.92+15.93

= 179.05 g/mol

Answer:

Salt domes storage has advantages in cost, security, environmental risk, and maintenance. Salt formations offer the lowest cost, most environmentally secure way to store crude oil for long periods of time. Stockpiling oil in artificially-created caverns deep within the rock-hard salt costs historically about $3.50 per barrel in capital costs. Storing oil in above ground tanks, by comparison, can cost $15 to $18 per barrel - or at least five times the expense. Also, because the salt caverns are 2,000-4,000 feet below the surface, geologic pressures will sea; any crack that develops in the salt formation, assuring that no crude oil leaks from the cavern. An added benefit is the natural temperature differential between the top of the caverns and the bottom - a distance of around 2,000 feet; the temperature differential keeps the crude oil continuously circulating in the caverns, giving the oil a consistent quality.

Answer:

713 nm. It is not visible with the naked eye.

Explanation:

Step 1: Given data

Step 2: Calculate the wavelength of the light

We will use the Planck-Einstein equation.

E = h × c / λ

λ = h × c / E

λ = 6.63 × 10⁻³⁴ J.s × 3.00 × 10⁸ m/s / 2.79 × 10⁻¹⁹ J

λ = 7.13 × 10⁻⁷ m

Step 3: Convert "λ" to nm

We will use the relationship 1 m = 10⁹ nm.

7.13 × 10⁻⁷ m × (10⁹ nm/1 m) = 713 nm

This light is not in the 400-700 nm interval so it is not visible with the naked eye.

Answer: The answer is the ''The moon is always lit up by the sun for us to see.''

Explanation: The moon is directly illuminated by the sun.

Answer: The particles are moving fast but close together.

Answer:

its in the explanation.

Explanation:

1.In liquids, particles are quite close together and move with random motion throughout the container. Particles move rapidly in all directions but collide with each other more frequently than in gases due to shorter distances between particles.

2.It assumes the shape of the part of the container which it occupies particles can move/slide past one another.

Hope this helps. :)

Answer:

Inductive reasoning

Explanation:

Inductive reasoning is based on making broad generalizations from specific observations. We draw conclusions from the data we have. This is the opposite of deductive reasoning, which starts with a general statement and aims to reach a specific conclusion.

Based on this, we can conclude that, if an investigator uses their knowledge, training, experience, and expertise to reach a conclusion, they are using inductive reasoning.

Answer:Because plastic products are durable, they can last for a long time. This makes them affordable because they do not have to be replaced often. On the other hand, the popular use of plastics means that many plastics are thrown away. Plastics litter the ocean, causing harm to marine birds and mammals. Plastic breaks down into plastic dust, which can last for up to a thousand years.

^^^^^copy and paste this part^^^^^

Explanation:Plastic is he hardest material to break down with harm to sea life and land life they may be affordable but costly to the environment.

Answer:

768g

Explanation:

We can use to formula [tex]N(A) = N_0(\frac{1}{2})^\frac{t}{t_{1/2}}[/tex] . Here, N(A) is the final amount. N0 is the initial amount. t is the time elapsed, and [tex]t_{1/2}[/tex] is the half life. Plugging in, we get the answer above.

The half life of I -137 is 8.07 days. if 24 grams are left after 40.35 days, 800 gram  were in the original sample.

The half-life (symbol t12) is the amount of time it takes for a volume (of material) to be reduced to half of its original value. In nuclear physics, the phrase is typically used to indicate how rapidly unstable atoms experience radioactive decay or even how long stable nuclei survive.

The phrase is sometimes used more broadly to describe any form of exponential (or, in rare cases, non-exponential) decay. The biological ½ of medications and other compounds in the human body, for example, is referred to in the medical sciences. In exponential growth, the inverse of half-life is doubling time.

ln P = kt + C

P = amount of I-137 at time t

C = constant

k = 1/time

t = time

1st condition:

P = Po, t = 0 days

2nd condition: (half-life)

P = 0.5Po, t = 8.07 days

3rd condition:

P = 25 grams, t = 40.35 days

Po = 800 grams

mass of I-137 = 800 gram

Therefore, 800 gram were in the original sample.

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Answer:

valence electrons

Explanation:

The valence electrons are the outer most electrons and the principal energy level in which they belong will vary for .

The chemical element which contains four (4) electrons in its third and outer main energy level is: Silicon (Si).

An electron shell can be defined as the outermost shell of an atom of a chemical element around the atomic nucleus.

Hence, an electron shell is an orbital that is typically accompanied by electrons around the nucleus of an atom.

A sublevel is also referred to as an orbital and it can be defined as an energy level that is associated with the electrons found outside the atomic nucleus.

In Chemistry, there are four main (4) types of sublevel and these are:

In the third (3rd) energy level, there are only three (3) sublevels and these are; s, p and d sublevels.

Silicon is a chemical element that is found in group (4) of the periodic table because it has four (4) electrons in its third and outermost shell.  

In its ground state, Silicon (Si) contains the following number of electrons:

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Answer:

The number 872 would be written as,

8.72× 10²

Explanation:

Scientific notation is used to express the large value in short form.

The number in scientific notation have two parts.

First part:

The digits (decimal point will place after first digit)

Second part:

× 10 ( the power which put the decimal point where it should be)

For example the number 872 would be written as

8.72× 10²

Another example:

6324.4 in scientific notation will be written as = 6.3244 × 10³

Answer: here is your answer

Explanation: You are visiting your Grandmother and notice that she is eating a balanced diet, taking vitamins, getting the proper amount of sleep and is not overweight. Despite her healthy lifestyle, she appears run down and tired. You realize that it's due to her lack of physical activity. Write a convincing letter to your grandma explaining the benefits of participating in regular physical activity.

Answer:

A-protons, B-nucleus, D-electrons, C-nucleus, E-electric cloud

Explanation:

The average atomic mass is given by the individual atomic masses of the isotope of the element and its percentage. The average atomic mass of the isotopic mixture is 159.8 g/mole.

Isotopes are atoms of the same element that have the same number of protons in their nucleus but have a different number of neutrons that alters their atomic masses. The relative abundance of the isotope of the element affects the average atomic mass of the mixture.

The formula for average atomic mass for the mixture of isotopes is given as:

Average atomic mass = ∑ (mass × abundance)

Given,

Abundance of isotope 1 = 22.00 %

Mass of isotope 1 = 159.3 g/mole

Abundance of isotope 2 = 78.00 %

Mass of isotope 2 = 161.2g/mole

Substituting values in the formula of average atomic mass as:

Average atomic mass = isotope 1 (mass × abundance) + isotope 2 (mass × abundance)

= (0.22) × (159.3) + (0.78) × (161.2)

= 34.046 + 125.736

= 159.8 g/mole

Therefore, the average atomic mass of the mixture of the two isotopes is 159.8 g/mole.

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Answer:

6 protons 8 neutrons 5 electrons

Explanation:

protons are blue neutrons are red electrons are green

Answer:

The mass of sodium chloride in the mixture is 18.75%

Explanation:

Here, we want to calculate the percentage of sodium chloride in the mixture.

The total mass of the mixture is 52 g + 12 g = 64 g

So the percentage mass of sodium chloride will be;

mass of sodium chloride/ Total mass * 100%

That will be: 12/64 * 100 = 18.75%

Answer:

Required heat = 2,259.36 N (approx)

Explanation:

Given:

Mass = 135 g

Specific heat (c) =4.184 J/gC

Change in temperature ΔT = 27-23 = 4 c

Find:

Required heat

Computation:

Q = mcΔT

Q = (135)(4.184)(4)

Required heat = 2,259.36 N (approx)

The heat transferred by the chemical reaction to the reservoir of a calorimeter containing 135 g of dilute aqueous solution is 2259.36 J

To solve this question, we'll begin by calculating the change in the temperature of the reservoir. This can be obtained as follow:

Initial temperature (T₁) = 23 °C

Final temperature (T₂) = 27 °C

ΔT = T₂ – T₁

ΔT = 27 – 23

Finally, we shall determine the heat transferred to the reservoir.

Change in temperature (ΔT) = 4 °C

Mass (M) = 135 g

Specific heat capacity (C) = 4.184 J/gºC

Q = MCΔT

Q = 135 × 4.184 × 4

Therefore, the heat transferred by the chemical reaction to the reservoir of a calorimeter containing 135 g of dilute aqueous solution is 2259.36 J

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Answer:

this atom has nine electrons

Answer:

B) The closer an electron is to the nucleus the lower it's energy level.

Explanation:

This is because the attractive force for electrons to the nucleus is stronger. Thus, the orbital energy becomes less.

Explanation:

Phosphorus (P) because of the 5 valence electrons total, 3 of them are in the 3p sublevel, and according to Hund's rule, they "single-fill" each orbital first.

Answer:Two Main Types of Pure Substances

Elements and compounds are the two types of pure substances. Examples of common elements include carbon, nitrogen and hydrogen. They consist of one type of atom and cannot break down into something else. Every pure carbon substance, for example, has the same particles in it.

Explanation:I think

Answer:

C

Explanation:

Hope this helps :)

Answer:

A. Cells are able to provide support

Answer:

SBr2

Electron geometry-tetrahedral; molecular geometry-trigonal pyramidal

PI4+

Electron geometry-tetrahedral; moleculargeometry-tetrahedralr

IBr2

Electron geometry - tetrahedral ; molecular shape - bent

Explanation:

We have to carefully consider the issues in question 2.

First of all, the compound SiF4 is an AX4 molecule so both it's electron domain geometry and molecular geometry are tetrahedral. The molecule has no lone pairs.

For SeF4, the compound is a molecule of the type AX4E, its molecular geometry is trigonal bipyramid but its molecular geometry is see-saw because of the presence of a lone pair of electrons on the central atom, selenium.

For XeF4, the electron domain geometry is octahedral but its molecular geometry is square planar. The molecule is of the type AX4E2 and the two lone pairs are positioned above and below the plane of the square.

Answer:

70.88 mL volume of 1.27 M of HCl is required.

Explanation:

Given data:

Initial volume = ?

Initial  molarity =  1.27 M

Final volume = 197.4 mL

Final molarity = 0.456 M

Solution:

Formula:

M₁V₁ = M₂V₂

Now we will put the values in formula.

1.27 M × V₁ =  0.456 M × 197.4 mL

V₁ = 0.456 M × 197.4 mL/1.27 M

V₁ = 90.014M.mL/1.27 M

V₁ = 70.88 mL

70.88 mL volume of 1.27 M of HCl is required.