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3 years ago

Expressed in the correct number of significant figures the sum of 0.53 cm + 75.321 cm + 28.1 cm =

Chemistry

1 answer:

Nadya [2.5K]3 years ago

5 0

Answer:

$\boxed{\text{104.0 cm}}$

Explanation:

When adding or subtracting values, you must round your answer to the same "place" as the measurement with its last significant figure furthest to the left.

That is, you round off to the same number of decimal places as the measurement with the fewest decimal places.

$\begin{array}{r|l}0.5& \text{3 cm}\\+ 75.3& \text{21 cm}\\+ 28.1 & \quad\text{cm} \\= 103.9 &\text{51 cm}\\\end{array}$

The measurement of 28.1 cm has one digit after the decimal point, so you round the sum to have only one digit to the right of the decimal.

However, the number to be dropped (51) is greater than 5 with only zeros or nothing following the 5.

You must round up the answer. You increase the last significant digit by one.

$\text{The sum is $\boxed{\textbf{104.0 cm}}$}$

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Answer:

The statement that best describes the trend in first ionization enery of elements on the periodic table is:

It generally decreases down a group because valence electrons are farther from the nucleus.

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As the atomic number of the atom increases (which is what happens when you go down a group) the furthest the outermost shell of electrons will be (the size of the atoms increases) and so those electrons require less energy to be released, which means that the ionization energy decreases.

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3 years ago

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As you climb a mountain, air pressure increases.

More force pushes on the air at the bottom of an air column.

As you descend a mountain, air molecules are closer together.

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3 years ago

How are superheavy elements made?

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3 years ago

1) Sodium hydroxide is deliquescent. A sample of 3.0 g was dissolved in 100 mL; 10 mL was titrated with 34.9 mL HCl 0.2 M. What

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From the calculation, the percentage of water in the sodium hydroxide sample is 7%.

<h3>What is neutralization?</h3>

The term neutralization has to do with the reaction between an acid and a base to yiled salt and water.

Now we have to apply the titration formula;

CAVA/CBVB = NA/NB

CA = concentration of acid

CB = concentration of base

VA = volume of acid

VB = volume of base

NA = number of moles of acid

NB = number of moles of base

The reaction equation is; HCl + NaOH ----->NaCl + H2O

CAVANB = CBVBNA

CB = CAVANB /VBNA

CB = 34.9 * 0.2 M * 1/10 * 1

CB = 0.698 M

Number of moles = Conncentration * volume

= 0.698 M * 100/1000 L = 0.0698 moles

Mass = Number of moles * molar mass

Mass = 0.0698 moles * 40 g/mol = 2.79 g

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Learn more about neutralization: brainly.com/question/15395418

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2 years ago

Convert 614 Cal to J. Only include the numerical value in your answer. Respond with the correct number of significant figures in

Kruka [31]

Answer:

Explanation:

Given parameters:

Number of given calories = 614 cal

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Now to convert the given calories to joule, we use the relationship below:

Since 1Cal gives 4.18Joule of energy

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This written as 2.57 x 10³J because it has three significant numbers of 2, 5 and 7.

In writing an operation that involves deducing the significant numbers, we simply express our answer to that shows the lowest number of significant numbers. Our problem has 3 significant numbers each and the answer is given in that regard.

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3 years ago