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mihalych1998 [28]
3 years ago
8

7. Which of the following is a proof that light travels in a straight line?

Chemistry
1 answer:
kotegsom [21]3 years ago
6 0

Answer:

formation of shadow is right

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Will a precipitate form from Pb(NO3)2(aq) and HCl(aq)?
Rus_ich [418]
1. Write out the formula Pb(NO3)2 (aq) + 2HCl (aq) ----> PbCl2 + 2HNO3 2. Use solubility guidelines (gotta memorize 'em) for the products to see if a solid forms Nitrates are always soluble so 2HNO3 (aq) Chlorides (Cl) are always soluble except for when you mix them with copper, lead, mercury, or silver. Since you mixed it with lead (Pb) it is solid and forms a precipitate. PbCl2 (s)
5 0
3 years ago
A wooden artifact from an ancient tomb contains 60% of the carbon-14 that is present in living trees. How long ago was the artif
noname [10]

Answer:

The age of the sample is 4224 years.

Explanation:

Let the age of the sample be t years old.

Initial mass percentage of carbon-14 in an artifact = 100%

Initial mass of carbon-14 in an artifact = [A_o]

Final mass percentage of carbon-14 in an artifact t years = 60%

Final mass of carbon-14 in an artifact = [A]=0.06[A_o]

Half life of the carbon-14 = t_{1/2}=5730 years

k=\frac{0.693}{t_{1/2}}

[A]=[A_o]\times e^{-kt}

[A]=[A_o]\times e^{-\frac{0.693}{t_{1/2}}\times t}

0.60[A_o]=[A_o]\times e^{-\frac{0.693}{5730 year}\times t}

Solving for t:

t = 4223.71 years ≈ 4224 years

The age of the sample is 4224 years.

8 0
3 years ago
For the reaction a2 + b2 → 2ab, ea(fwd) = 105 kj/mol and ea(rev) = 77 kj/mol. assuming the reaction occurs in one step, calculat
Lady bird [3.3K]
Answer is: 28 kJ.
Chemical reaction: A₂ + B₂ ⇄ 2AB.
Ea(forward) = 105 kJ/mol.
Ea(reverse) = 77 kJ/mol.
ΔH(reaction) = ?
<span>The enthalpy change of reaction is the change in the energy of the reactants to the products.
</span>ΔH(reaction) = Ea(forward) - Ea(reverse).
ΔH(reaction) = 105 kJ/mol - 77 kJ/mol.
ΔH(reaction) = 28 kJ/mol; this is endothermic reaction (ΔH <span>> 0).</span>

6 0
3 years ago
Why should you prefer dry ashing to wet ashing of food sample such as cabbage​
julia-pushkina [17]

Answer:

Wet ashing is primarily used in the preparation of samples for subsequent analysis of specific minerals . It breaks down and removes the organic matrix surrounding the minerals so that they are left in an aqueous solution

Explanation:

8 0
3 years ago
Plz help this was due yesterday butttttt i didn’t want to do it...
sergejj [24]
So what am I suppose to answer here?
8 0
3 years ago
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