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andrew-mc [135]
3 years ago
9

A change that produces one or more new substances is called _____.

Chemistry
2 answers:
Vesnalui [34]3 years ago
7 0

Answer:

the answer is c

Explanation:

a chemical change mean it changes it for ever and a physical change mean it can be changed back and evaporation means it turns solid water in to gas hope this helps

garik1379 [7]3 years ago
6 0

Answer:

\Large \boxed{\mathrm{B. \ a \ chemical \ change}}

Explanation:

A chemical change always produces one or more new substances that differs from the initial matter before the change.

The products and reactants both, of a chemical change, can be one or more substances before the change and after the change.

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After many generations, which trait will be most common? Why?
allsm [11]

It would be sadness because people have been going thru alot of things over the years

6 0
3 years ago
Air, with an initial absolute humidity of 0.016 kg water per kg dry air, is to be dehumidified for a drying process by an air co
amid [387]

Answer:

(a) The proportion of dry air bypassing the unit is 14.3%.

(b) The mass of water removed is 1.2 kg per 100 kg of dry air.

Explanation:

We can express the proportion of air that goes trough the air conditioning unit as p_{d} and the proportion of air that is by-passed as p_{bp}, being p_{d}+p_{bp}=1.

The amount of water that goes into the drier inlet has to be 0.004 kg/kg, and can be expressed as:

0.004 = 0.016*p_{bp}+ 0.002*p_{d}

Replacing the first equation in the second one we have

0.004 = 0.016*(1-p_{d})+ 0.002*p_{d}=0.016-0.016*p_{d}+0.002*p_{d}\\0.004 - 0.016 = (-0.016+0.002)*p_{d}\\-0.012 = -0.014*p_{d}\\p_{d}=\frac{-0.012}{-0.014}=0.857\\\\p_{bp}=1-p_{d}=1-0.857=0.143

(b) Of every kg of dry air feed, 85.7% goes in to the air conditioning unit.

It takes (0.016-0.002)=0.014 kg water per kg dry air feeded.

The water removed of every 100 kg of dry air is

100 kgDA*0.857*0.014 kgW/kgDA= 1.1998 \approx 1.2 kgW

It can also be calculated as the difference in humiditiy between the inlet and the outlet: (0.016-0.004=0.012 kgW/kDA) and multypling by the total amount of feed (100 kgDA).

100 * 0.012 = 1.2 kgW

7 0
4 years ago
Find the number of molecules in .815 mole of O2​
Simora [160]

Answer:

4.9 × 10²³ molecules

Explanation:

Given data:

Number of molecules = ?

Number of moles of oxygen = 0.815 mol

Solution:

The given problem will solve by using Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.

The number 6.022 × 10²³ is called Avogadro number.

1 mole = 6.022 × 10²³ molecules

0.815 mol  ×  6.022 × 10²³ molecules  / 1 mol

4.9 × 10²³ molecules

6 0
3 years ago
Oxygen-17 and oxygen-18 _____. have the same mass are isotopes of oxygen have different numbers of protons
NNADVOKAT [17]

 oxygen -17   and  oxygen-18 are  isotopes  of  oxygen


<em><u>Explanation</u></em>

Isotope is two or more forms   of the same element  that  has  equal  amount of proton but different  number of neutrons  in the nuclei.

oxygen -17 and oxygen-18  are  isotope    of oxygen since they  have the equal amount   of  protons but different   number of  neutrons  in their  nuclei.

that  is oxygen  17  has   8  protons  and  9  neutrons  while  oxygen 18  has  8 protons and  10  neutrons.


8 0
3 years ago
A student performed a serial dilution on a stock solution of 1.33 M NaOH. A 1.0 mL aliquot of the stock NaOH (ms) was added to 9
serg [7]

Answer:

The correct answer is 1.33 x 10⁻⁵ M

Explanation:

The concentration of the stock solution is: C= 1.33 M

In the first dilution, the student added 1 ml of stock solution to 9 ml of water. The total volume of the solution is 1 ml + 9 ml = 10 ml. So, the first diluted concentration is:

C₁= 1.33 M x 1 ml/10 ml = 1.33 M x 1/10 = 0.133 M

The second dilution is performed on C₁. The student added 1 ml of 0.133 M solution to 9 ml of water. Again, the total volume is 1 ml + 9 ml = 10 ml. The second diluted concentration is:

C₂= 0.133 M x 1 ml/10 ml = 0.133 M x 1/10= 0.0133 M

Since the student repeated the same dilution process 3 times more (for a total of 5 times), we have to multiply 5 times the initial concentration by the factor 1/10:

Final concentration = initial concentration x 1/10 x 1/10 x 1/10 x 1/10 x 1/10

                                = initial concentration x (1/10)⁵

                                = 1.33 M x 1 x 10⁻⁵

                                = 1.33 x 10⁻⁵ M

3 0
3 years ago
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