Answer:
2.34 gms left
Explanation:
3 weeks = 21 days = 7 half lives
300 * (1/2)^7 = 2.34 gms
Answer:
Dmitri Mendeleev
Explanation:
Dmitri Mendeleev a Russian Chemist arranged elements on the periodic table according to their atomic mass. He used this arrangement to predict some of the properties of the missing element.
- Dmitri Mendeleev around 1869 described the periodic table.
- The table was based on the periodic law which states that "chemical properties of elements are a periodic function of their atomic weights".
- In the Mendeleev table, elements are arranged by atomic weights with recurring properties in a periodic manner.
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Answer:
Helium is created from hydrogen in the sun's core.
Four hydrogen-1 nuclei fuse to produce
- one helium-4 nucleus, two neutrons,
- two positrons, and
- two electron neutrinos.
Explanation:
Step One:
.
Two hydrogen-1 nuclei fuse. One proton will convert to a neutron. The products will be
- one hydrogen-2 nucleus,
- one positron, and
- one electron neutrino.
Step Two:
.
There are plenty of hydrogen-1 nuclei available in the core of the sun. The hydrogen-2 nucleus from step one will fuse with a hydrogen-1 nucleus. The product is
Step Three
.
Two helium-3 nuclei from step two react with each other. The products are:
- one helium-4 nucleus, and
- two hydrogen-1 nuclei.
The overall reaction will be:
.

In other words, hydrogen nuclei in the core of the sun fuse together to form helium.
Answer:
27.4 g/mol
Explanation:
Assuming the compound is a gas and that it behaves ideally, we can solve this problem by using the <em>PV=nRT formula</em>, where:
- V = 245 mL ⇒ 245 mL / 1000 = 0.245 L
- R = 0.082 atm·L·mol⁻¹·K⁻¹
<u>Inputting the data</u>:
- 1.22 atm * 0.245 L = n * 0.082 atm·L·mol⁻¹·K⁻¹ * 298 K
<u>Solving for n</u>:
With the <em>calculated number of moles and given mass</em>, we <u>calculate the molar mass</u>:
- 0.334 g / 0.0122 mol = 27.4 g/mol