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julia-pushkina [17]
3 years ago
7

Which explains the basis of the Biuret test? a. Under base conditions, copper ions bind to the amino groups of proteins and chan

ge color. b. Iodine fits into the coils of starch polymers and changes color. c. A blue dye binds to protein and changes color.d. Sudan III dye binds to lipids and changes color.

Chemistry
2 answers:
nasty-shy [4]3 years ago
7 0

Answer:Answer: Under base conditions, copper ions bind to amino groups of proteins and change colour.

Explanation: Biuret test is a general test for detecting the presence of a peptide bond in a compound. It is a test for proteins. Amino acids are joined together in proteins by peptide bonds. Copper ions from blue alkaline solution of CuSO4 react with amino groups of proteins to give a violet colored complex called a biuret compound

Ugo [173]3 years ago
3 0

Answer:A

Explanation:

In the Biuret test, the copper ions bind covalently to the amino groups as shown in the image to form a violet complex. This violet complex is responsible for the colour change as shown

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Suppose a group of volunteers is planning to build a park near a local lake. The lake is known to contain low levels of arsenic
Kisachek [45]

Answer:

A) 10.75 is the concentration of arsenic in the sample in parts per billion .

B) 7,633.66 kg the total mass of arsenic in the lake that the company have to remove.

C) It will take 1.37 years to remove all of the arsenic from the lake.

Explanation:

A) Mass of arsenic in lake water sample = 164.5 ng

The ppb is the amount of solute (in micrograms) present in kilogram of a solvent. It is also known as parts-per million.

To calculate the ppm of oxygen in sea water, we use the equation:

\text{ppb}=\frac{\text{Mass of solute}}{\text{Mass of solution}}\times 10^9

Both the masses are in grams.

We are given:

Mass of arsenic = 164.5 ng = 164.5\times 10^{-9} g

1 ng=10^{-9} g

Volume of the sample = V = 15.3 cm^3

Density of the lake water sample ,d= 1.00 g/cm^3

Mass of sample =  M = d\times V=1.0 g/cm^3\times 15.3 cm^3=15.3 g

ppb=\frac{164.5\times 10^{-9} g}{15.3 g}\times 10^9=10.75

10.75 is the concentration of arsenic in the sample in parts per billion.

B)

Mass of arsenic in 1 cm^3  of lake water = \frac{164.5\times 10^{-9} g}{15.3}=1.075\times 10^{-8} g

Mass of arsenic in 0.710 km^3 lake water be m.

1 km^3=10^{15} cm^3

Mass of arsenic in 0.710\times 10^{15} cm^3 lake water :

m=0.710\times 10^{15}\times 1.075\times 10^{-8} g=7,633,660.130 g

1 g = 0.001 kg

7,633,660.130 g = 7,633,660.130 × 0.001 kg=7,633.660130 kg ≈ 7,633.66 kg

7,633.66 kg the total mass of arsenic in the lake that the company have to remove.

C)

Company claims that it takes 2.74 days to remove 41.90 kilogram of arsenic from lake water.

Days required to remove 1 kilogram of arsenic from the lake water :

\frac{2.74}{41.90} days

Then days required to remove 7,633.66 kg of arsenic from the lake water :

=7,633.66\times \frac{2.74}{41.90} days=499.19 days

1 year = 365 days

499.19 days = \frac{499.19}{365} years = 1.367 years\approx 1.37 years

It will take 1.37 years to remove all of the arsenic from the lake.

3 0
3 years ago
If you mix cu2+ with? a. nacl, b. nano2, c. h2o , arrange the solutions based on their absorption from highest frequency to lowe
erica [24]

The arrangement of the solutions based on their absorption from highest frequency to lowest frequency :

b.NaNO_{2} > c.H_{2} O > a.NaCl

<h3>What is absorption frequency?</h3>
  • The frequency of the molecular vibration that led to the absorption is the same as the absorption frequency of a basic IR absorption band.
  • In a way, an emission spectrum is the opposite of an absorption spectrum.
  • The discrepancies in the energy levels of each chemical element's orbitals correspond to absorption lines for each chemical element at various particular wavelengths.
  • Therefore, it is possible to identify the constituents in a gas or liquid using its absorption spectrum.
  • Absorption spectroscopy is most frequently used to measure infrared, atomic, visible, ultraviolet (UV), and x-ray waves.

Learn more about Absorption frequency here:

brainly.com/question/5032775

#SPJ4

3 0
1 year ago
You have a mass of 54 kg and are sitting on a stool. The normal force the stool applies on you is ...
Karo-lina-s [1.5K]

Answer:

529.2 N

Explanation:

As we have studied the first law of motion, which states that every action has some reaction, equal in magnitude but having an opposite direction.

The force that is acting on the student will be due to gravitational force, that is equal to his weight.

                                              F=mg: 54kg x 9.8m/s^2 =529.2 N

So the weight of student is exerting downwards towards the stool and land. The stool will also exert a force on the student that will be equal in magnitude but opposite in direction, then it will be 529.2 N.

This is because the student is sitting in a constant state and all the weight is exerted on the stool.

Note: This answer is very generic supposing that all the weight of the student is on stool. But, if we suppose that student's legs are on floor so it means the force of gravity acting on the stool has become less because student's mass on stool is less. So the answer would be a force somehow less than 529.2 N.  However, since the question asked normal force, it would be weight of student in general terms.

Hope it helps!

7 0
2 years ago
In a sample of oxygen gas at room temperature, the average kinetic energy of all the balls stays constant. Which postulate of ki
Levart [38]

Answer:

Collisions between gas particles are elastic; there is no net gain or loss of kinetic energy.

Explanation:

When a gas is paced in a container, the molecules of the gas have little or no intermolecular interaction between them. There is a lot of space between the molecules of the gas.

The gas molecules move at very high speed and collide with each other and with the walls of container.

The collision of these particles with each other is perfectly elastic hence the kinetic energy of the colliding gas particles do not change.

7 0
3 years ago
What makes physical change a physical change and a chemical change a chemical change
Snowcat [4.5K]
A physical change is any change in a substances form that does not change its chemical makeup. Examples of physical changes are breaking a stick or melting ice. A chemical change occurs when atoms of a substance are rearranged, and the bonds between the atoms are broken or formed. HOPE THIS HELPS!!
6 0
2 years ago
Read 2 more answers
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