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Alla [95]
3 years ago
12

When making observations during an experiment, which of the following must be included? a. Descriptions of the appearance of any

chemicals used. b. Explanations for why certain steps were carried out analysis of results. c. Descriptions of any changes in the system following an action. d. Descriptions of any non-changes in the system following an action a list of possible errors.
Chemistry
1 answer:
sweet [91]3 years ago
8 0

Answer:When making observations during an experiment, Descriptions of any changes in the system following an action and Descriptions of any non-changes in the system following an action a list of possible errors must be included. The correct option is C and D.

Explanation: During a scientific experiment procedures, observation is usually carried out to take into consideration an active information from the natural source. Data can be collected by the observer:

- quantitatively ( by counting and measuring data when numerical values are attached.

- qualitatively ( when the presence or absence of a property is noted). Hence, option C and D are correct.

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Calculate the oxidation state of the underlined elements of K2 Cr2 O7
Semenov [28]

Answer:

+4

Explanation:

In PbO2, oxygen exhibits an oxidation number of -2 (since it's not a peroxide or superoxide):

Let the oxidation number of Pb be x. Then, for the compound to be neutral, the oxidation numbers of all atoms should add up to zero.

⇒ x + (−2) + (−2) = 0

x = +4

So the oxidation no. of Pb is +4.

I hope this helps.

3 0
3 years ago
Rusting of iron is a very common chemical reaction. It results in one form from Fe reacting with oxygen gas to produce iron (III
Vlada [557]

<u>Answer:</u> The given amount of iron reacts with 9.0 moles of O_2 and produce 6.0 moles of Fe_2O_3

<u>Explanation:</u>

We are given:

Moles of iron = 12.0 moles

The chemical equation for the rusting of iron follows:

4Fe+3O_2\rightarrow 2Fe_2O_3

  • <u>For oxygen gas:</u>

By Stoichiometry of the reaction:

4 moles of iron reacts with 3 moles of oxygen gas

So, 12.0 moles of iron will react with = \frac{3}{4}\times 12.0=9.0mol of oxygen gas

  • <u>For iron (III) oxide:</u>

By Stoichiometry of the reaction:

4 moles of iron produces 2 moles of iron (III) oxide

So, 12.0 moles of iron will produce = \frac{2}{4}\times 12.0=6.0mol of iron (III) oxide

Hence, the given amount of iron reacts with 9.0 moles of O_2 and produce 6.0 moles of Fe_2O_3

5 0
3 years ago
Describe the difference beetween an extensive and intesive property
olasank [31]

Extensive properties, such as mass and volume, depend on the amount of matter being measured. Intensive properties, such as density and color, do not depend on the amount of the substance present. Physical properties can be measured without changing a substance's chemical identity.

7 0
3 years ago
PLEASE HELP ME ILL GIVE BRAINLIEST IF YOU EXPLAIN UR ANSWER
Marina CMI [18]
The contraction of the triceps muscle causes the arm to flex. The contraction of the triceps muscle causes the arm to extend. When added to the force of the biceps contracting it provides extra force to the ball.

The answer is A
5 0
3 years ago
Read 2 more answers
Table Salt or NaCl is composed of sodium and chlorine. While the individual elements of sodium and chlorine are very reactive, t
Deffense [45]

Answer:

Chlorine is more likely to steal a valence electron from sodium.

Explanation:

Sodium is number 11 on the periodic table with one valence electron. Belonging to the first group, it's one of the alkali metal, which are known to be highly reactive. Chlorine is number 17 with seven valence electrons, and it's in the second-to-last group of halogens--also very reactive.

Considering that elements with one valence electron are just about 100% likely to give up electrons to reach a stable state, sodium would be the element that is more likely to lose its valence electron to chlorine. In other words, chlorine would be the electron thief.

5 0
3 years ago
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