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nignag [31]
3 years ago
15

What is the composition of an isotope of calcium (atomic number 20)?

Chemistry
2 answers:
anzhelika [568]3 years ago
6 0

Answer:

The answer to your question is: last option.

20 protons

20 electrons

25 neutrons

Explanation:

Data

Calcium, atomic number 20

Atomic number indicates the number of protons in an element, so, if Calcium's atomic number is 20, it means that it has 20 protons.

In a neutral element, the number of protons = number of electrons, then

Calcium has 20 electrons.

Only the number of neutrons could change.

According to the previous description, the last option is correct.

beks73 [17]3 years ago
4 0

Answer:

i think c

Explanation:

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What is the total pressure of air in lungs of an individual with oxygen at 100. mmHg, nitrogen at 573 mmHg, carbon dioxide at 0.
ryzh [129]

Answer: The total pressure of air in lungs of an individual is 760.28 mm Hg

Explanation:

According to Dalton's law, the total pressure is the sum of individual pressures.

p_{total}=p_A+p_B+p_C...

Given : p_{total} =total pressure of gases = ?

p_{O_2} = partial pressure of oxygen = 100 mm Hg

p_{N_2} = partial pressure of nitrogen = 573 mm Hg

p_{CO_2} = partial pressure of Carbon dioxide = 0.053 atm = 40.28 mm Hg(1 atm = 760 mmHg)

p_{H_2O} = partial pressure of water vapor = 47 torr = 47 mm Hg  (1torr=1 mm Hg)

putting in the values we get:

p_{total}=(100+573+40.28+47)mmHg

p_{total}=760.28mmHg

Thus the total pressure of air in lungs of an individual is 760.28 mm Hg

5 0
3 years ago
Express 0.08010 in exponential notation to the proper significant figures
nataly862011 [7]
This would be 8.010 * 10^-2
3 0
3 years ago
A sample of carbon dioxide is contained in a 250.0 mL flask at 0.930 atm and 15.4 °C. How many molecules of gas are in
Yanka [14]

Answer:

We are given:

Volume (V) = 0.25 L

Pressure (P) = 0.93 atm

Temperature (T) = 15.4°C  OR   288.4 K

<u>Solving for the number of moles of CO₂:</u>

From the ideal gas equation:

PV = nRT

replacing the variables

0.93 * 0.25 = n (0.082)(288.4)

n = 0.00983 moles

<u>Number of molecules:</u>

Number of moles=  0.00983

number of molecules in 1 mole = 6.022 * 10²³

Number of molecules in 0.00983 moles = 0.00983 * 6.022 * 10²³

Number of molecules = 5.91 * 10²¹

8 0
2 years ago
1. What kind of diagram shows how energy flows from one organism to another?
shusha [124]
It would be D.the food chain
5 0
2 years ago
The half-life of a radioactive isotope is the amount of time it takes for a quantity of that isotope to decay to one half of its
Sedaia [141]

Radio active decay reactions follow first order rate kinetics.

a) The half life and decay constant for radio active decay reactions are related by the equation:

t_{\frac{1}{2}} =\frac{ln 2}{k}

t_{\frac{1}{2}} = \frac{0.693}{k}

Where k is the decay constant

b) Finding out the decay constant for the decay of C-14 isotope:

Decay constant (k) = \frac{0.693}{t_{\frac{1}{2}}}

k = \frac{0.693}{5230 years}

k = 1.325 * 10^{-4} yr^{-1}

c) Finding the age of the sample :

35 % of the radiocarbon is present currently.

The first order rate equation is,

[A] = [A_{0}]e^{-kt}

\frac{[A]}{[A_{0}]} = e^{-kt}

\frac{35}{100} = e^{-(1.325 *10^{-4})t}

ln(0.35) = -(1.325 *10^{-4})(t)

t = 7923 years

Therefore, age of the sample is 7923 years.

3 0
3 years ago
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