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qaws [65]
3 years ago
12

A pound is approximately 0.45 kilogram. A person weighs 87 kilograms. What is the person’s weight, in pounds, when expressed to

the correct number of significant figures?
A. 190 lb
B. 180 lb
C. 52 lb
D. 39 lb

Chemistry
2 answers:
Vinvika [58]3 years ago
6 0

Answer:

190 pounds  

Explanation:

Given that  

A pound is approximately 0.45 kilogram

A person weighs 87 kilograms

Now change the unit form kilogram to pounds as follows:

 

1 pound / 0.45 kilogram * 87 kilograms

= 193.3 pounds

Now expressed to the correct number of significant figures

193.3 pound = 190 pounds  

Sauron [17]3 years ago
4 0

Answer:

87 kilograms =191.8 pounds

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Rama09 [41]

Answer:

2. they are the smallest unit of matter

6 0
3 years ago
How many moles of CaCI are present in 60.0mL of a 0.10 M CaCI2 solution?
balandron [24]

Answer:

0.006 mol of CaCl2 are present

Explanation:

Use dimensional analysis for this:

60.0 mL CaCl2/1  * 1 L/1000 mL * 0.10 mol/1 L = 0.006 mol

If you were to write this as fractions out on paper, you'll see that all of the units will cancel out and you'll be left with moles of CaCl2.

**REMEMBER** that molarity (M) is talking about how many moles of that substance is present in one Liter of solvent.

Hope this helps :)

4 0
3 years ago
Which of the following compounds has the highest boiling point.
nlexa [21]
Answer:
            1-<u>Pentanol </u>has the highest boiling point.

Explanation:
                   Boiling points of given compounds are as follow,

                 1) 2-Pentanone  =  101 °C

                 2) 1-Pentanol  =  138 °C

                 3)  Pentane  =  36.1 °C

                 4)  Pentanal  =  103 °C

Pentanol has greatest boiling point as compare to others because it involes a strongest intermolecular interactions called as hydrogen bond interactions. Remaining compounds lack the direct attachement of hydrogen to most electrnegative atom like oxygen which is present in 1-Pentanol.
4 0
3 years ago
Illustrate the x- and y-axes to show the reaction pathway and potential energy, in kilojoules. Ensure your energy intervals are
Rufina [12.5K]

Answer:

Enthalpy of a reaction = P - R  

Synthesis: ΔH = 25 kJ - (-30 kJ) = 55 kJ  

Single Replacement: ΔH = 30kJ - 65 kJ = -35 kJ  

Double Replacement: ΔH = 60 kJ - 10 kJ = 50 kJ

Explanation:

6 0
3 years ago
Rutherfordium-261 has a half-life of 1.08 min. How long will it take for a sample of rutherfordium to lose one-third of its nucl
Ira Lisetskai [31]

Answer:

t=1.712min

Explanation:

Hello!

In this case, since the radioactive decay equation is:

\frac{A}{A_0}=2^{-\frac{t}{t_{1/2} }

Whereas A stands for the remaining amount of this sample and A0 the initial one. In such a way, since the sample of rutherfordium is reduced to one-third of its nuclei, the following relationship is used:

A=\frac{1}{3} A_0

And we plug it in to get:

\frac{\frac{1}{3} A_0}{A_0}=2^{-\frac{t}{t_{1/2}} } \\\\\frac{1}{3}=2^{-\frac{t}{t_{1/2}} }

Now, as we know its half-life, we can compute the elapsed time for such loss:

log(\frac{1}{3})=log(2^{-\frac{t}{t_{1/2}} })\\\\log(\frac{1}{3})=-\frac{t}{t_{1/2}} }*log(2)

t=-\frac{log(\frac{1}{3})t_{1/2}}{log(2)} \\\\t=1.71min

Best regards!

8 0
2 years ago
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