Answer:
Protons carry a positive electrical charge and they alone determine the charge of the nucleus. Adding or removing protons from the nucleus changes the charge of the nucleus and changes that atom's atomic number. For example, adding a proton to the nucleus of an atom of hydrogen creates an atom of helium.
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Answer:
One gram helium gas is equal to the 4.002602 g/mole
Explanation:
Helium gas is a gas or chemical element. The symbol of helium gas is He and the atomic number of this gas is 2. This gas is colorless, odorless, and tasteless. It is a non-toxic gas. It is found in the periodic table in the first place.
Helium is a very lightest gas and very abundant in nature in the universe. It is present in the universe around 24 percent. Helium is also called by another name that titan of sun. This is detected by the yellow line. The liquid form of helium gas is called cryogenics. This helium gas is used in lifting balloons and airplanes.
Answer:
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Explanation:
A <em>first order reaction</em> follows the law:
![rate=k[A]](https://tex.z-dn.net/?f=rate%3Dk%5BA%5D)
, where [A] is the concentraion of the reactant A.
Equivalently:
![\dfrac{d[A]}{dt}=-k[A]](https://tex.z-dn.net/?f=%5Cdfrac%7Bd%5BA%5D%7D%7Bdt%7D%3D-k%5BA%5D)
Integrating:
![\dfrac{d[A]}{[A]}=-kdt](https://tex.z-dn.net/?f=%5Cdfrac%7Bd%5BA%5D%7D%7B%5BA%5D%7D%3D-kdt)
![\ln \dfrac{[A]}{[A_o]}=-kt](https://tex.z-dn.net/?f=%5Cln%20%5Cdfrac%7B%5BA%5D%7D%7B%5BA_o%5D%7D%3D-kt)
Half-life means [A]/[A₀] = 1/2, t = t½:
That means that the half-life is constant.
The slope of the plot of ln [N₂O₅] is -k. Then k is equal to 6.40 × 10⁻⁴ min⁻¹.
Thus, you can calculate t½:
t½ = ln(2) / 6.40 × 10⁻⁴ min⁻¹
t½ = 1,083 min.
Rounding to 3 significant figures, that is 1,080 min.
Answer:
D
Explanation:
Identifying unique features of evidence
