Answer:
- <u><em>3.30 × 10³ years</em></u>
Explanation:
1) <u>Carbon-14 disintegration rate of a young (alive) tree</u>: 0.266 per second per gram.
2)<u> Carbon-14 disintegration rate of a wood sample prepeared from an object recovered at an archaelogical excavation (dead matter):</u> 0.178 per second per gram.
3) <u>Ratio of decay</u>: A/A₀ = 0.178 / 0.266 = 0.669
4) <u>Half-life equation</u>: A/A₀ = (1/2)ⁿ, where n is the number of half-lives since the object died.
5) <u>Substitute and solve for n</u>:
That means that 0.578 half-life has elapsed since the wood with which the object was created was dead matter.
6) <u>Convert number of half-lives to years</u>:
- 0.578 half-life × 5715 years/half-life = 3,303 years = 3.30 × 10³ years.
Answer:
a) positive feedback
Explanation:
positive as in increasing
Answer:
Water-gas A mixture of carbon monoxide (CO) and hydrogen (H2) produced by passing steam over red-hot coke using the endothermic reaction C + H2O # CO + H2.
Explanation:
From the given choices, aluminum oxide is the only ionic
compound there. The ions present are Al3+ and O2-. Aluminum is a
chemical compound of aluminum and oxygen with the chemical formula Al2O3. It is
the most frequently happening of numerous aluminum oxides, and precisely recognized
as aluminum (III) oxide.
<span>Molds are created to achieve a
specific design of a material. These materials either came from a process of
having a higher or lower temperature. Therefore, the molder must have thermal
resistant properties. Low melting points means that the material to be shaped
came from a cooler process. Wood and metal have higher thermal conductivity and
therefore can easily be cooled. The wax can turn really hard and can be
unbreakable when present in colder materials due to the lipids present in it. Clay
however can become a mold because of its low melting point.</span>
