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LiRa [457]
3 years ago
13

A sample taken from a layer of mica in a canyon has 2.10 grams of potassium-40. A test reveals it to be 2.6 billion years old. H

ow much
potassium-40 was in the sample originally if the half-life of potassium-40 is 1.3 billion years?
A. 4.20
B. 8.40 g
c. 12.6 g
D. 16.8 g
E. 25.2 g
Chemistry
2 answers:
Katyanochek1 [597]3 years ago
8 0

Answer:

The correct answer is b

Explanation:

Arte-miy333 [17]3 years ago
4 0

Answer:

Correct Answer is (B)

Explanation:

Got it right on plato Chemistry Post test

<em>Hope I helped you out :)</em>

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Given the reaction 2NO2 1/202 N2O5, what is the relationship between the rates of formation of N,0, and disappearance of the two
daser333 [38]

Answer:

r=\frac{r(NO_{2})}{2} =\frac{r(O_{2})}{1/2}=\frac{r(N_{2}O_{5})}{1}

Explanation:

Let us consider the reaction:

2 NO₂ + 1/2 O₂ ⇄ N₂O₅

The rate of formation of a substance is equal to the change in concentration of the product divided the change in time:

r(N_{2}O_{5})=\frac{\Delta [N_{2}O_{5}] }{\Delta t}

The rate of disappearance of a reactant is equal to to the change in concentration of the reactant divided the change in time, with a negative sign so that the rate is always a positive variable.

r(NO_{2})=-\frac{\Delta[NO_{2}] }{\Delta t}

r(O_{2})=-\frac{\Delta[O_{2}] }{\Delta t}

The rate of the reaction is equal to the rate of any substance divided its stoichiometric coefficient. In this way, we can relate these expressions:

r=\frac{r(NO_{2})}{2} =\frac{r(O_{2})}{1/2}=\frac{r(N_{2}O_{5})}{1}

8 0
3 years ago
Which of the following are bound to hemoglobin when hemoglobin is in the r-state? choose all that apply.
Mademuasel [1]
Even though there is no followings, I will try to include in this answer all the possible answers. I am sure about two elements that bound to hemoglobin when hemoglobin is in the R-state :Fe+2 and O2. As you should know, <span> R-state of hemoglobin is a relaxed form that is also called</span> <span>oxyhemoglobin, so the O2 definitely must be mentioned in there.</span>
7 0
3 years ago
8. How much heat, in kilojoules, is needed to produce 1850 grams of ammonia (NH3),
AleksAgata [21]

Based on the enthalpy of the reaction, 41625 kJ of heat is needed to produce 1850 grams of ammonia (NH3).

<h3>What is heat of reaction?</h3>

The heat of reaction or enthalpy change is the heat absorbed or evolved when reactant molecules react to form products.

According the enthalpy value of the reaction, 4 moles of ammonia require 1530 kJ of heat for its formation.

Molar mass of ammonia = 17 g

Mass of 4 moles of ammonia = 4 × 17 = 68 g

1850 g of ammonia will require = 1850 × 1530/68 = 41625 kJ of heat.

Therefore, 41625 kJ of heat is needed to produce 1850 grams of ammonia (NH3).

Learn more about enthalpy at: brainly.com/question/14047927

#SPJ1

6 0
2 years ago
Select all of the answers that apply. what are the two main ingredients in air? oxygen carbon dioxide nitrogen helium hydrogen
RSB [31]
Carbon dioxide and nitrogen
8 0
3 years ago
Read 2 more answers
Proteins have many functions in the cell membrane. Which function is NOT related to a protein?a. transportb. membrane fluidityc.
kirill115 [55]

The function that is NOT related to a protein is:

Membane fluidity.

Membrane fluidity is not related to a protein function because membrane fluidity is a function of lipids not proteins.

Transport and all other options are involved in functions of protein.

5 0
1 year ago
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