An investigator proposes a study to determine the clinical relevance of a new assay technique to measure minimal residual disease (MRD) in adolescent (age 14-16) cancer patients undergoing chemotherapy. The study requires that two additional bone marrow aspirates be performed during the course of chemotherapy. The subject's chemotherapy will not be altered based on the results of the assay technique measures. However, future patients with cancer would benefit from improved interventions based on study findings. The IRB determined that the activity was a minor increase over minimal risk. Which of the following statements best describes the IRB approval requirements for involving adolescent cancer patients in the research study?

Assent is not required, however, both parents must give permission for the inclusion of the adolescent child.
Assent of the child only is required.
Assent is not required, however, one parent must give permission for the inclusion of the adolescent in this study.
Assent of the child and permission of both parents are required.

Answer:

three electrons were transferred in the process

Explanation:

The electrode potential of the cathode is

E°cathode= E°cell + E°anode

E°cathode = 2.35V + (-0.74V)

E°cathode= 1.61 V

Let us look at the reduction half equation; the oxidation half equation must be;

Oxidation half equation;

Cr(s) ----> Cr^3+(aq) + 3e

The reduction half equation must now be

Reduction half equation;

3Ce^4+(aq) + 3e ----> 3Ce^3+(aq)

This implies that three electrons were transferred in the process as shown by the balanced half cell reaction equations.

Answer:

helium , krypton,xenon,radon, argon are noble gasses

answer is 20

explanation: total Pressure = 205

partial pressure of N = 143

partial pressure of He = 41

total pressure = partial pressure of N + partial pressure of O + partial pressure of He

partial pressure of O = 205 - 185 = 20

Answer:

20

Explanation:

Answer:

they won

Explanation:

Answer:

Mass no= 16

and atomic no= 7

Explanation:

mass number is equals to number of protons + number of neutrons .

atomic number is equals to number of protons .

Answer:

balancing of charges of both sides

Answer:

A

Explanation:

A...............................

Answer:

306.6g/mol

Explanation:

To calculate molecular weight you need to know how many grams ou have in a determined amount of moles of substance. As you have the mass of the sample (1.42g), you need to find how many moles are, as follows:

The reaction of the acid HX with the base YOH is:

HX + YOH → H₂O + YX

1 mole of acid reacts per mole of base.

In a titration, the solution turned pink when moles base = moles acid.

Moles of base that the student added (Using the volume and molarity of the solution) are:

32.48mL = 0.03248L ₓ (0.1426 moles base / L) = 0.004632 moles of base

As the titration is in equivalence point, there are 0.004632 moles of the acid

Molecular weight (Ratio between grams of sample and its moles) is:

1.42g / 0.004632 moles =

Answer:

venus

Explanation:

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Answer: I would say that Saturn is most like Earth. Not only does it have moons, like Earth, but the atmosphere is also denser like Earth. It also has windstorms, granite they are much more intense than Earth’s, but they do indeed happen. Saturn also has hydrogen gas; this gas is here on Earth supporting life in our ocean. Therefore, there is a chance that the conditions on Saturn could provide the essentials for there to be life.

Answer:

Yes, at 20 °C the tank was filled to full capacity

Explanation:

Given;

let initial pressure, P₁ = 2.37 atm

let initial volume, V₁ = 1860 L

let final pressure, P₂ = 220 bar = 217.123 atm

let final volume, V₂ = ?

Subject the air volume (1860 L )  at 2.37 atm to the tank rating (220 bar)

Ideal law is given by;

PV = nRT

At a fixed mole and gas temperature, the equation becomes;

P₁V₁ = P₂V₂

V₂ = (P₁V₁) / P₂

V₂ = (2.37 x 1860) / 217.123

V₂ = 20.3 L

After subjecting the air volume to tank rating, the volume of the air at 220 bar is 20.3 L which is greater than tank volume (18 L).

The extra 2.3 L can be assumed to be compressed gas volume due to the given (lower) temperature.

Thus, at 20 °C the tank was filled to full capacity.

Answer:

D. mid-ocean ridges

Explanation:

The location where seafloor spreading occurs is at mid-ocean ridges. Therefore option 4 is correct.

Mid-ocean ridges are underwater mountain ranges that extend through the Earth's oceans. They are formed by the tectonic plates diverging or moving apart from each other.

As the plates separate, magma rises from the mantle to fill the gap, creating new oceanic crust. The molten material solidifies to form new seafloor, which then moves away from the ridge in opposite directions.

Seafloor spreading is a key process in plate tectonics and the continuous renewal of the Earth's crust.

It leads to the expansion of the ocean basins and the formation of new crust, contributing to the overall movement and reshaping of the Earth's lithosphere.

Therefore, the correct answer is option 4: mid-ocean ridges.

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Answer:

5.31×10¯²³ g.

Explanation:

Data obtained from the question include:

Molar weight of O2 = 32 g/mol

Mass of 1 oxygen atom =..?

From Avogadro's hypothesis, we understood that 1 mole of any substance contains 6.02×10²³ atoms.

This implies that 1 mole of O2 also contains 6.02×10²³ atoms.

1 mole of O2 = 32 g

The mass of 1 atom of O2 can be obtained as follow:

32 g of O2 contains 6.02×10²³ atoms.

Therefore Xg of O2 will contain 1 atom i.e

Xg of O2 = 32/6.02×10²³

Xg of O2 = 5.31×10¯²³ g

Therefore, the mass of a single oxygen atom is 5.31×10¯²³ g.

The mass of a single oxygen atom is 5.31 x 10⁻²³ grams. Therefore, option D is correct.

The molecular weight of oxygen gas is 32 g/mol. To find the mass of a single oxygen atom, divide the molecular weight by Avogadro's number (6.022 x 10²³ atoms/mol).

Avogadro's number (6.022 x 10²³) represents the number of particles (atoms, molecules, or ions) in one mole of a substance.

To find the mass of a single oxygen atom, divide the molecular weight of oxygen gas by Avogadro's number:

Mass of a single oxygen atom = (32 g/mol) / (6.022 x 10²³ atoms/mol)

Simplifying the expression:

Mass of a single oxygen atom = 5.31 x 10⁻²³ g

Therefore, the mass of a single oxygen atom is 5.31 x 10⁻²³ grams.

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The question is incomplete, the complete question is;

Consider a pure crystalline solid that is heated from absolute zero to a temperature above the boiling point of the liquid. Which of the following processes produces the greatest increase in the entropy of the substance? A ) melting the solid B ) heating the gas C ) vaporizing the liquid D ) heating the solid E ) heating the liquid

Answer:

vaporizing the liquid

Explanation:

We generally define entropy in chemistry as the degree of disorderliness in a system. The entropy of gases is greater than that of liquids and the entropy of liquids is greater than that of solids. It then logically follows that the degree of entropy in gases is the greatest among all the states of matter while the entropy of solids is the least among all the states of matter since solid particles remain in their mean positions and can only vibrate or sometimes rotate. Liquid particles may translate while gaseous particles move at high velocity with negligible intermolecular forces of attraction between them.

A phase transition from liquid to gaseous state now represents the greatest change in the entropy of the system since gases posses the highest entropy among all the states of matter, hence the answer.

Answer:

2I4O9_4I +9O

Explanation:

Complex compound (

I

4

O

9

) is broken down to form

I

2

and

O

2

Answer:

Decomposition

Explanation:

Because it went from one compound to two elements.

Answer:

(i) hydrolysis; (ii) combination;  (iii) single replacement;  

(iv) single replacement; (v) double replacement

Explanation:

(i) Carbohydrates are broken down to form glucose

Carbohydrates must react with water to form glucose.

For example,

C₆H₁₁O₅-O-C₆H₁₁O₆ + H-O-H ⟶ 2C₆H₁₂O₆

       maltose                                          glucose

This is a hydrolysis reaction — the reaction of a compound in which a molecule of water breaks one or more bonds to form new substances.

The reaction is not a decomposition (a reaction in which a compound breaks down into two or more simpler substances), because two different molecules are involved.

(ii) Tarnishing of copper.

Cu + S ⟶ CuS

This is a combination or synthesis reaction — in which two or more substances combine to form a single new substance.

(iii) Heating of ferric oxide with aluminium powder

Fe₂O₃ + 2Al ⟶ Al₂O₃ + 2Fe

This is a single displacement or single replacement reaction — in which one element replaces another element in a compound.

Here, Al is replacing Fe in its oxide.

(iv) Blue colour of copper sulphate solution disappears when zinc dust is added to it

CuSO₄ + Zn ⟶ ZnSO₄  + Cu

This is a single displacement or single replacement reaction.

Here, Zn is replacing Cu in its sulfate.

(v) Dilute sulfuric acid is added to sodium hydroxide solution  

H₂SO₄ + 2NaOH ⟶ Na₂SO₄ + 2H₂O

2H⁺, SO₄²⁻ + 2Na⁺OH⁻ ⟶ 2Na⁺, SO₄²⁻ + 2H-OH

This is a double displacement or double replacement reaction — in which the positive and negative ions of two ionic compounds exchange places to form two new compounds.

The Na⁺ ions are replacing the H⁺ ions in the sulfuric, forming sodium sulfate and water,  

Answer:

Partial pressure of H₂ = 0.9556 atm

Explanation:

Given:

Barometric pressure = 753 torr

Vapor pressure of water = 26.74 torr

FInd:

Partial pressure of H₂

Computation:

Partial pressure of H₂ = Barometric pressure - Vapor pressure of water

Partial pressure of H₂ = 733 - 26.74  

Partial pressure of H₂ = 726.26 torr

1 atm = 760 torr

So,

Partial pressure of H₂ = 726.26/760

Partial pressure of H₂ = 0.9556 atm

Answer: the answer is B estimation

Explanation:

i just took a test

The one that is represented by the number of significant figures in a quantity is scientific notation. The correct option is D.

Scientific notation is a method of expressing numbers that are either too large or too small to be written in decimal form.

In the United Kingdom, it is known as scientific form, standard index form, or standard form.

The proper scientific notation format is an x 10b, where an is a number or decimal number with an absolute value greater than or equal to one and less than ten, or 1 |a| 10. b is the power of ten required for scientific notation to be mathematically equivalent to the original number.

Scientific notation is represented by the number of significant figures in a number.

Thus, the correct option is D.

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Answer:

a chemical change

Explanation:

a physical change is mostly identified even without indicators i.e candle wax about forming a new acid or base I guess we have to include a ph scale to ascertain since the salt can be acidic but not necessarily an acid

Answer: The answer is A, a chemical change has occurred

Explanation:

I’m just a jenious

The number of protons and neutrons together makes the total atomic mass of the element. The atom of chromium has 28 neutrons. Thus, option b is correct.

An atomic mass is the property of an element that defines the number of protons and neutrons of the atom placed in a periodic table. The atomic mass is represented at the lower half of the atomic symbol.

The atomic mass is the sum of the neutrons and the protons that are held together in the nucleus of the atom as a concentrated mass. The atomic number is given as,

Atomic number = number of protons + number of neutrons

Given,

The atomic mass of chromium = 52

Number of protons = 24

Substituting values above:

52 = 24 + number of neutrons

number of neutrons = 52-24

= 28

Therefore, the number of neutrons of a chromium atom is 28.

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Answer: option b, 28

Explanation:

Deliquescent substances are solids that absorb moisture from the atmosphere until they dissolve in the absorbed water and form solutions. Efflorescent: Efflorescent substances are solids that can undergo spontaneous loss of water from hydrated salts.

Answer:

Option (1)

Explanation:

When two or more substances are chemically combined in a fixed proportion of mass, substance formed is a compound.

Properties of a compound are different from the properties of the elements from which the compound is formed.

If Magnesium (Mg) is burned in the presence of Oxygen (O₂), Magnesium oxide (MgO) is formed.

Properties of MgO are different from Mg and O₂ because MgO is a COMPOUND.

Option (1) will be the answer.

Answer:

The metre is defined as the length of the path travelled by light in a vacuum in 1/299 792 458 of a second.

Answer:

+91.7 KJmol-1

Explanation:

Recall that ∆G= -RTlnK

Since ∆G in this case is ∆Grxn and K is the Ksp

Note that the Ksp is the solubility product (as shown by the reaction equation)

∆Grxn is the change in free energy for the reaction, in this case the ionization of the silver iodide into silver and iodide ions.

R= 8.314JK-1 and T =25°C +273 = 298 K (the centigrade temperature must be appropriately converted to its corresponding absolute absolute before proceeding with the calculation)

Hence we can substitute values accordingly;

∆Grxn = -(8.314 × 298 × ln 8.3×10^-17)

∆Grxn = +91.7 KJmol-1

Answer:

The Kₐ of the weak acid is 1.033×10⁻⁴

Explanation:

The dissociation of a weak acid in aqueous solution is limited to about 5 to 10%

The acid dissociation reaction is given as follows;

HA (aq) + H₂O (l) → H₃O⁺(aq) + A⁻ (aq)

Given that the pH = 2.5, we have

pH = -log₁₀[H₃O⁺] = 2.5

∴ [H₃O⁺] = 10^(-2.5) = 0.0031623

[tex]K_a = \dfrac{[H_3O^+][A^-]}{[HA]}[/tex]

Kₐ = [H₃O⁺][A⁻]/[HA] = (0.0031623^2)/(0.1 - 0.0031623) = 1.033×10⁻⁴

The acid dissociation constant, Kₐ for weak acid is very low as obtained

Answer:

The filament of a bulb has a high melting point because of the heat generated inside the bulb.

Explanation:

When electricity is concentrating and run through a bulb, it starts to generate heat. Leave it on long enough and it will start to build up a lot of heat. Have you ever tried touching a light bulb when it has been all day? It's scorching to the skin.

Since electricity generates heat, the bulb's filament has to have a high melting point so it doesn't melt, destroy the bulb, and leave you light-less. If the filament has a high melting point, then it is able to withstand heat generated by electricity and provide you light.

The question is incomplete, the complete question is;

Atom Number of protons Number of electrons Number of neutrons

1 39 39 52

2 40 40 50

3 39 39 54

4 40 40 51

Based on the information that is given, which atom in the table has the highest mass?

a. 1

b. 2

c. 3

d. 4

Answer:

c

Explanation:

The relative atomic mass is given as; number of protons + number of neutrons. If we take the relative atomic mass of each of the options;

1) 39 +52 = 91

2) 40+50 = 90

3) 39 + 54 = 93

4) 40 + 51 = 91

Thus 3 has the highest mass as seen above, hence the answer given.

Answer: Since oxygen is in group 6 on the periodic table, its valency is  

2 −

and hence so is its oxidation number.

But there are 2 oxygen atoms for each carbon atom so the total negative charge due the oxygen is  

4 −

But since a molecule must have a net charge of zero in the free form, it implies that the oxidation number of the carbon atom must then be  

+ 4

Answer:

[tex]\large \boxed{\sf subatomic \ particles}[/tex]

Explanation:

The smaller particles in an atom are called subatomic particles. Subatomic particles include electrons, protons, and neutrons.

Answer:

By giving electricity to copper compound solution.

Explanation:

Electrolysis is one of the major way of refined copper. The copper containing solution has two electrodes.i) positive electrodes called anode. ii) negative electrodes called cathode. When electricity is pass into the copper containing solution electrolysis process is starts and impure copper is formed in anode and pure copper is formed in cathode.

So, We can get pure copper in cathode through electrolysis.

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A - convection

B - conduction

C - radiation

D - convection