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Luba_88 [7]
4 years ago
10

Ling decided to do a science project on exercise. She wanted to find out how long it takes for a person's heart rate to slow dow

n to normal after exercise.Which of the following was likely the scientific prediction Ling made about her project?
A.
My heart beats 60 times each minute.
B.
Exercise is important.
C.
A person's heart rate slows down in three minutes.
D.
I found out that my heart beat slows down after five minutes.
Chemistry
1 answer:
forsale [732]4 years ago
8 0
C- a persons heart rate slows down after 5 minutes.
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37.2 liters of a gas has a pressure of 362.43 kPa at 46.5 °C. If the pressure increases to
Nataliya [291]

Answer:

Option A. 25.7 L.

Explanation:

Step 1:

Data obtained from the question. This include the following:

Initial volume (V1) = 37.2 L

Initial pressure (P1) = 362.43 kPa

Initial temperature (T1) = 46.5 °C

Final pressure (P2) = 693.9 kPa

Final temperature (T2) = 149.2 °C

Final volume (V2) =.?

Step 2:

Conversion of celsius temperature to Kelvin temperature.

This can be achieved as shown below:

Temperature (K) = Temperature (°C) + 273

T (K) = T (°C) + 273

Initial temperature (T1) = 46.5 °C

Initial temperature (T1) = 46.5 °C + 273 = 319.5 K.

Final temperature (T2) = 149.2 °C

Final temperature (T2) = 149.2 °C + 273 = 422.2 K.

Step 3:

Determination of the new volume.

This can be obtained by using the general gas equation as shown below:

Initial volume (V1) = 37.2 L

Initial pressure (P1) = 362.43 kPa

Initial temperature (T1) = 319.5 K

Final pressure (P2) = 693.9 kPa

Final temperature (T2) = 422.2 K

Final volume (V2) =.?

P1V1/T1 = P2V2/T2

362.43×37.2/319.5 = 693.9 × V2/422.2

Cross multiply

319.5×693.9×V2 = 362.43×37.2×422.2

Divide both side by 319.5 × 693.9

V2 = (362.43×37.2×422.2)/(319.5×693.9)

V2 = 25.7 L

Therefore, the new volume is 25.7 L.

8 0
4 years ago
Magnesium has 12 electrons. How many electrons will be orbiting in the outermost shell, farthest away from the nucleus?
erica [24]

Answer:

Magnesium has an outer energy level of n=3 with two electrons in in its energy level. Therefor Magnesium has 2 valance electrons.

Explanation:

4 0
3 years ago
The fact that all living organisms can be classified into distinct families, groups, and orders provides _ which supports the Sc
dmitriy555 [2]
It provides evidence 
8 0
3 years ago
when 2.40 moles of sodium react with 5.90 moles of chlorine gas in the reaction shown above, how many moles of sodium chloride a
frutty [35]

First we look at the chemical reaction:

2 Na + Cl₂ → 2 NaCl

Now we should see which is the limiting reagent, so we construct the following reasoning:

if        2 moles of Na reacts with 1 mole of Cl₂

then   2.4 moles of Na reacts with X moles of Cl₂

X = (2.4 × 1) / 2 = 1.2 mole of Cl₂ (way lower that the available quantity of chlorine).

So the limiting reagent is sodium, and from here we can calculate the number of moles of NaCl produced.

if        2 moles of Na produces 2 moles of NaCl

then   2.4 moles of Na produces Y moles of NaCl

Y = (2.4 × 2) / 2 = 2.4 moles fo NaCl (sodium chloride)

3 0
3 years ago
It is possible to determine the ionization energy for hydrogen using the Bohr equation. Calculate the ionization energy for an a
liraira [26]

Answer:

B. 2.18\times 10^{-18}\ J

Explanation:

Ionization energy is the minimum amount of energy which is required to knock out the loosely bound valence electron from the isolated gaseous atom.

The expression for the energy of an electron in the nth orbit is:-

E_n=-2.18\times 10^{-18}\times \frac{1}{n^2}\ Joules

For transitions:

Energy\ Difference,\ \Delta E= E_f-E_i =-2.18\times 10^{-18}(\frac{1}{n_f^2}-\frac{1}{n_i^2})\ J=2.18\times 10^{-18}(\frac{1}{n_i^2} - \dfrac{1}{n_f^2})\ J

\Delta E=2.18\times 10^{-18}(\frac{1}{n_i^2} - \dfrac{1}{n_f^2})\ J

Given, n_i=1\ and\ n_f=inifinity

\Delta E=2.18\times 10^{-18}(\frac{1}{1^2} - \dfrac{1}{\infty^2})\ J

\Delta E=2.18\times 10^{-18}\ J

<u>Ionization energy, \Delta E=2.18\times 10^{-18}\ J </u>

5 0
3 years ago
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