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3 years ago

When diagramming an atom, the electron shells ____________ the nucleus must be filled first?

1 answer:

4 0

Concept: According to the basic concept of the electronic configuration of the element, the electron can be filled first in those shell which has least energy or (n +l) value. Here, n is the principal quantum number on shell and l is the azimuthal quantum number.

Since, the first shell has least value of energy in any atom. So, it should be filled first.

Hence, the correct statement can be written as;

When diagramming an atom, the electron shells _nearest to _ the nucleus must be filled first.

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This reaction is sometimes used to inflate life rafts, weather balloons, and the like, where a simple, compact means of generati

tia_tia [17]

Answer: 10.2 grams

Explanation:

The balanced chemical reaction is :

$CaH_2(s)+2H_2O(l)\rightarrow Ca(OH)_2(aq)+2H_2(g)$

According to the ideal gas equation:

$PV=nRT$

P = Pressure of the gas = 740 torr = 0.97 atm (760torr=1atm)

V= Volume of the gas = 12.0 L

T= Temperature of the gas = 19°C = 292 K $0^0C=273K$

R= Gas constant = 0.0821 atmL/K mol

n= moles of gas

$n=\frac{PV}{RT}=\frac{0.97\times 12.0}{0.0821\times 292}$

$n=0.48$

According to stoichiometry:

2 moles of hydrogen are generated by = 1 mole of $CaH_2$

Thus 0.48 moles of hydrogen are generated by = $\frac{1}{2}\times 0.48=0.24$ moles of $CaH_2$

Mass of $CaH_2=moles\times {\text {Molar mass}}=0.24mol\times 42g/mol=10.2g$

Thus 10.2 grams of $CaH_2$ are needed to generate 12.0 L of hydrogen gas if the pressure of hydrogen is 740. torr at 19°C

5 0

3 years ago

How do ethical concerns affect scientific research

Gwar [14]

Answer:

Ethical concerns affect scientific research by adding boundaries to what can and cant be experimented on. An example is that its socially unacceptable to experiment on humans because its considered wrong and horrific, even at the expense of learning more about human nature and/or the human body.

7 0

3 years ago

What is the mass, in grams of a pure iron cube that has a volume of 4.20cm^3

Dmitriy789 [7]

$d_{Fe}=7874\frac{kg}{m^{3}}=7,874\frac{g}{cm^{3}}\\
V=4,2cm^{3}\\\\
m=dV=7,784\frac{g}{cm^{3}}*4,2cm^{3}\approx 32,7g$

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3 years ago

Espresso Coffee House is designing a coffee mug that keeps liquids hot. The research department tested several different materia

raketka [301]

Answer:

This question is incomplete

Explanation:

This question is incomplete because the result of the described experiment would have better determined the type of scientific explanation to profer. However, the type of material that will preserve the relative hotness or temperature of the hot coffee for the longest time will be a material than can resist heat transfer. These materials tend to keep hot substances hot by not allowing the heat of the coffee to be conducted or pass through it. These materials are mostly insulators or made by placing an insulator between two heat conductors.

Generally, heat is usually transferred from a region of higher concentration to a region of lower concentration, hence when the heat is denied of this transfer, the heat will remain trapped in the "heat-donor" substance (in this case the hot coffee). Thus, the material chosen (A, B or C) will be the material that resists heat transfer the most based on the explanation above.

4 0

3 years ago

Molecules are the smallest units of matter with the characteristic properties of a substance.

Vilka [71]

False, Atoms are the smallest units of matter that display both the chemical and physical properties of it, based on the structure of the atom.

3 0

3 years ago