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3 years ago

Which term describes a change that occurs with no new substances being formed?

Chemistry

1 answer:

Elina [12.6K]3 years ago

8 0

C. physical change

Explanation:

That's the answer

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3 years ago

How many oxygen molecules are in 5.17g of oxygen gas

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3 years ago

Which of the following pieces of laboratory glassware should be used to most accurately measure out a 25.00 ml sample of a solut

wel

Answer:

The correct answer is 25 mL graduated cylinder (it should be used in all the cases)

Explanation:

In order to measure 25.00 ml sample of a solution it should be used a 25 mL graduated cylinder, as it is previously and properly calibrated. The other laboratory glassware, beaker and erlenmeyer, have graduations which are approximate, so they are used when exact volumes are not needed.

ii) graduated cylinder has the least uncertainly. It is more accurate than a beaker or erlenmeyer (to within 1%)

iii) A 25 mL graduated cylinder should be used because it is the most accurate lab glassware (between those were mentioned: beaker, erlenmeyer).

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4 years ago

When dilute HCL is added to zinc pieces taken in a test tube

Romashka-Z-Leto [24]

Answer:

zince chloride will be formed and hydrogen gas will be librated.

Explanation:

When dilute HCl is added to zinc pieces, a rection will takes place as follows :

$Zn+HCl\rightarrow ZnCl_2+H_2$

It means that zinc chloride will form when zinc reacts with dilute HCL. Also hydrogen gas will produced.

As zinc is more reactive than hydrogen, it displaces hydrogen from its solution and forms zinc chloride. The form product is white in color and H₂ is an odorless gas.

Hence, zince chloride will be formed and hydrogen gas will be librated.

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3 years ago

You are the medical examiner at the scene of a murder at a restaurant. There is a

Hoochie [10]

The compound : C₄₀H₄₄N₄O

<h3>Further explanation</h3>

The empirical formula is the smallest comparison of atoms of compound =mole ratio of the components

The principle of determining empirical formula

• Determine the mass ratio of the constituent elements of the compound.

• Determine the mole ratio by dividing the percentage by the atomic mass

The mol ratio of composition : C : H : N : O

$\tt \dfrac{80.66}{12}\div \dfrac{7.39}{1}\div \dfrac{9.39}{14}\div \dfrac{2.68}{16}\\\\6.722\div 7.39\div 0.671\div 0.1675\rightarrow divide~by~smallest(0.1675)\\\\40\div 44\div 4\div 1$

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3 years ago