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Which action is the best example of a direct observation

luda_lava [24]

Since you didn't have any extra information about the question I'll be presenting an example from my own textbooks that I've used.

An example of a direct observation is listening to a cricket chirp at night, and counting the number of chirps per minute.

Direct Observation is where the evaulator watches the subject in their usual habitat without disrupting or altering it.

3 0

3 years ago

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An easy way to assign the number of d-electrons (the â€śd countâ€ť) in a transition metal ion is to first look at the periodic t

Lorico [155]

Chromium is in Group 6, so elemental chromium has 6 valence electrons. Therefore, chromium 3+ has three 3d-

6 0

3 years ago

3.5g of a Certain compound X, known to be made of carbon, hydrogen, and perhaps oxygen, and to have a molecular molar mass of 15

shutvik [7]

Answer:

C₅H₁₀O₅

Explanation:

1. Calculate the mass of each element in 2.78 mg of X.

(a) Mass of C

$\text{Mass of C} = \text{5.13 g CO}_{2}\times \dfrac{\text{12.01 g C}}{\text{44.01 g }\text{CO}_{2}}= \text{1.400 g C}$

(b) Mass of H

$\text{Mass of H} = \text{2.10 g H$_{2}$O}\times \dfrac{\text{2.016 g H}}{\text{18.02 g H$_{2}$O}} = \text{0.2349 g H}$

(c) Mass of O

Mass of O = 3.5 - 1.400 - 0.2349 = 1.87 g

2. Calculate the moles of each element

$\text{Moles of C = 1400 mg C}\times\dfrac{\text{1 mmol C}}{\text{12.01 mg C }} = \text{116.6 mmol C}\\\\\text{Moles of H = 234.9 mg H} \times \dfrac{\text{1 mmol H}}{\text{1.008 mg H}} = \text{233.1 mmol H}\\\\\text{Moles of O = 1870 mg O} \times \dfrac{\text{1 mmol O}}{\text{16.00 mg O}} = \text{116 mmol O}$

3. Calculate the molar ratios

Divide all moles by the smallest number of moles.

$\text{C: } \dfrac{116.6}{116.6}= 1\\\\\text{H: } \dfrac{233.1}{116.6} = 1.999\\\\\text{O: } \dfrac{116}{116.6} = 1.00$

4. Round the ratios to the nearest integer

C:H:O = 1:2:1

5. Write the empirical formula

The empirical formula is CH₂O.

6. Calculate the molecular formula.

EF Mass = (12.01 + 2.016 + 16.00) u = 30.03 u

The molecular formula is an integral multiple of the empirical formula.

MF = (EF)ₙ

$n = \dfrac{\text{MF Mass}}{\text{EF Mass }} = \dfrac{\text{150 u}}{\text{30.03 u}} = 5.00 \approx 5$

MF = (CH₂O)₅ = C₅H₁₀O₅

The molecular formula of X is C₅H₁₀O₅.

8 0

3 years ago

Hydrogen bonds form between neighboring water molecules because of ________. A. electron transfer B. electron sharing C. the vis

Oduvanchick [21]

Answer:

Answer is B.

Explanation:

Hydrogen bonds forms when hydrogen atom is attracted towards oxygen atom of other water. A proton is shared by two ion electrons pair in which oxygen atom is partially negatively charged while hydrogen atom is partially positively charged.

7 0

3 years ago

Suppose a student did not fully redissolve the Al(OH)3 that initially formed upon the addition of H2SO4. Predict and explain how

kirza4 [7]

<span>Percent yield is the measured recovery of a substance in grams divided by the theoretical amount of substance expected in grams (times 100 to convert to %). Undissolved Aluminum trihydroxide would add mass to the Aluminum sulphate one is making here. The measured mass would be inaccurately high, increasing the percent yield calculated.</span>

6 0

3 years ago