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3 years ago

Is hand washing a chemicals change or physicals change and why?

Chemistry

2 answers:

Alona [7]3 years ago

6 0

Wouldn’t it be a chemical change because you’re using soap? So chemical change.

PolarNik [594]3 years ago

4 0

Answer:

If you wash your hands with soap, the soap molecules act as a link between the water you're washing with and the oil on your skin.

Explanation:

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Choose all that apply: Living organisms use atoms from sugar molecules combined with other elements to form: Question 9 options:

Lina20 [59]

Living organisms use atoms from sugar molecules combined with other elements to form lipids and nucleic acids. Lipids are hydrophobic organic compounds composed of carbon and a high ratio of hydrogen to oxygen. Nucleic acids are an acidic polymer of nucleotides found or produced in the cell nucleus.

8 0

3 years ago

Una disolución contiene 40% de ácido acético en masa. La densidad de la disolución es de 1.049 g/mL a 20°C. Calcule la masa de á

s344n2d4d5 [400]

Answer:

52.45g

Explanation:

The computation of the mass of pure acetic acid in 125mL of this solution is shown below:

The percentage of mass would be equivalent to the g of solute in each 100g of water

As we know that

density = mass ÷ volume

So,

Volume = mass ÷ density

V = 100g / 1.049 (g / ml)

V = 95.328 mL

Now In every 95,328 ml of C_2H_4O_2 there are 40g of C_2H_4O_2

i.e.

each 125ml of C_2H_4O_2 there are 52.45g

SO,

x = 40g. 125ml ÷ 95.328

x = 52.45g

4 0

3 years ago

A drop of vinegar ( a weak acid ) is placed on a sample of each of the materials below. Which will show the most active reaction

professor190 [17]

Answer: Option (B) is the correct answer.

Explanation:

Marble is also known as calcium carbonate and its chemical formula is $CaCO_{3}$ .

When it combines with vinegar then it results in the formation of calcium acetate which is a water soluble compound along with the release of carbon dioxide which occurs in the form of bubbles and water.

The reaction is as follows.

$CaCO_{3} + CH_{3}COOH \rightarrow Ca(CH_{3}COOH)_{2} + H_{2}O + CO_{2}$

Whereas vinegar being a weak acid will not react with glass, copper and steel.

8 0

3 years ago

Read 2 more answers

To interconvert the concentration units molality (m) and mass percent, you must also know the density of the solution. A) True B

uranmaximum [27]

Answer:

The correct answer is option false.

Explanation:

Molality of the solution defined as moles of substance present in 1 kilogram of solvent.

Moles = $\frac{Mass of solute}}{\text{molar mass of solute}}$

$Molality=\frac{Moles}{\text{Mass of solvent(kg)}}$

Mass of percent (w/w%) of the solution is defined as amount of solute present in 100 grams of solution.

$(w/w\%)_=\frac{\text{Mass of solute}}{\text{Mass of solution}}\times 100$

So, if want to inter-convert molality into mass percent we can do that without knowing density of solution.

Mass of solution = Mass of solute + Mass of solvent

7 0

3 years ago

CAN ANYONE PLEASE HELP MY BOOKS ARENT HELPING!!!! THIS IS FOR FIRE TECH

Mazyrski [523]

Answer:

The answer to the question is;

The occupant load of the store having a floor area of 100,000 ft² is 3,317.86 persons.

Explanation:

Based on NFPA guidelines we have for sales on street floor, the allowable occupant load factor per person is 30 ft²

That is where the floor area is 100,000 square feet we have the number of allowable occupant given by

(100,000 ft²)/(30 ft²/Person) = $\frac{10000}{3} Persons$ or 3,333 persons

That is the occupant load of the store if the floor area is 100,000 square feet = 3,333 persons

Based on m² we have 9,290 m² will require 2.8 m²/person

which gives;

(9,290 m²)/(2.8 m²/person) = $\frac{9290}{2.8} Persons$ = 23225/7 or 3,317.86 persons

Therefore applying safety, we go with the lesser number and we have

The occupant load of the store having a floor area of 9,290 m² = 3,317.86 persons.

5 0

3 years ago