Answer:

Explanation:
Hola,
En este caso, podemos usar la ley de Boyle, la cual nos permite analizar el comportamiento volumen-presión en un gas ideal de manera inversamente propocional:

Así, dado el volumen y la presión inicial, la cual se convierte a atmósferas (760 torr = 1atm), calculamos el volumen final a 1 atm como se muestra a continuación:

Saludos!
Answer:
He developed the concept of concentric electron energy levels
Explanation:
Before Bohr's model, Rutherford's model was proposed. This model explains most of the properties of the atom but failed to explain the stability of the atom.
As per Rutherford's model, electrons revolve around the nucleus in the orbit.
But revolving electron in their orbit around nucleus would give up energy and so gradually move towards the nucleus and therefore, eventually collapse.
Bohr's proposed that the electrons around the nucleus move orbit of fixed energy called "stationary states". Electrons in these stationary states do not radiate energy.
Therefore, proposal of concentric electron energy levels refine the atomic models.
Answer: 72 grams of
are needed to completely burn 19.7 g 
Explanation:
According to avogadro's law, 1 mole of every substance weighs equal to molecular mass and contains avogadro's number
of particles.
To calculate the number of moles, we use the equation:

Putting in the values we get:


According to stoichiometry:
1 mole of
requires 5 moles of oxygen
0.45 moles of
require=
moles of oxygen
Mass of 
72 grams of
are needed to completely burn 19.7 g 
Explanation:
atomic hydrogen torch utilizes an electric arc whereby two closely - but not touching electrodes - result in the release of powerful electric spark as the current tries to flow through the gap. The gap is filled with hydrogen gas in an atomic hydrogen torch rather than air. The electric arch is split the hydrogen gas molecules into hydrogen atoms (some in plasma form). When the hydrogen atoms land on cooler objects like the metal being welded or cut, they region back to H₂ molecules releasing enormous amounts of heat on the surface. Surface temperatures can reach 4000 °C. The use of hydrogen gas protects the metal being welded from oxidation. Oxidation may compromise the quality of the weld.
Learn More:
For more on other welding torches check out;
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