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Leya [2.2K]
3 years ago
7

An archaeologist finds 14C in a sample of material to be decaying at 20 Geiger Counter clicks per second. A modern equivalent sa

mple of the same material decays at 160 clicks per second. The half-life of 14C is 5,730 years. How old is the sample
Chemistry
1 answer:
Kay [80]3 years ago
4 0

Answer:

17188 years

Explanation:

Recall the formula;

0.693/t1/2 = 2.303/t log(No/N)

t1/2 = half life of 14C

No = initial activity of 14C

N = activity of 14C at time t

t = age of the sample

Substituting values

0.693/5730= 2.303/t log(160/ 20)

1.21 * 10^-4= 2.0798/t

t = 2.0798/1.21 * 10^-4

t = 17188 years

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There are three sets of sketches below, showing the same pure molecular compound (hydrogen chloride, molecular formula ) at thre
RideAnS [48]

Answer:

The correct answer is - option C.

Explanation:

Given: the melting point of HCl is

-114.8 °C, which suggests that below this temperature HCl will be solid.

and, since the boiling point of HCl is - 85.1 °C. It is also suggested that above this temperature HCl will be gas, Therefore.

Solid -114.8  - Ordered arrangement

Liquid -85.1c  - Less orderly arranged

Gaseous - Least orderly arranged

Thus, at —90 °C, HCl will be present 'in the liquid state,  At — 1 °C, HCl will be present in the gaseous state and at -129 °C, HCl will be present in the solid-state. So, the molecules will be organized in a more orderly manner .

Thus, the correct answer is - option C

8 0
4 years ago
Cerebrum is made of ____ matter? 4 letter word
katen-ka-za [31]
Gray matter hope this helps!
7 0
3 years ago
Read 2 more answers
A 232-lb fullback runs the 40-yd dash at a speed of 19.8 ± 0.1 mi/h.
Neporo4naja [7]

Answer:

(a)  7.11 x 10⁻³⁷ m

(b)  1.11 x 10⁻³⁵ m

Explanation:

(a)  The de Broglie wavelength is given by the expression:

λ = h/p = h/mv

where h is plancks constant, p is momentum which is equal to mass times velocity.

We have all the data required to calculate the wavelength, but first we will have to convert the velocity to m/s, and the mass to kilograms to work in metric system.

v = 19.8 mi/h x ( 1609.34 m/s ) x ( 1 h / 3600 s ) = 8.85 m/s

m = 232 lb x ( 0.454 kg/ lb ) = 105.33 kg

λ = h/ mv = 6.626 x 10⁻³⁴ J·s / ( 105.33 kg x 8.85 m/s ) = 7.11 x 10⁻³⁷ m

(b) For this part we have to use the uncertainty principle associated with wave-matter:

ΔpΔx > = h/4π

mΔvΔx > = h/4π

Δx = h/ (4π m Δv )

Again to utilize this equation we will have to convert the uncertainty in velocity to m/s for unit consistency.

Δv = 0.1 mi/h x ( 1609.34 m/mi ) x ( 1 h/ 3600 s )  

     = 0.045 m/s

Δx = h/ (4π m Δv ) = 6.626 x 10⁻³⁴ J·s / (4π x 105.33 kg x 0.045 m/s )

     = 1.11 x 10⁻³⁵ m

This calculation shows us why we should not be talking of wavelengths associatiated with everyday macroscopic objects for we are obtaining an uncertainty of 1.11 x 10⁻³⁵ m for the position of the fullback.

5 0
3 years ago
1. Mg2+ and Ca2+ are in the same group on the periodic table. In terms of electronic
finlep [7]

Answer:

Se detailed explanation.

Explanation:

Hello,

In this case, since both magnesium and calcium ions are in group IIA, we can review the following similar properties:

- Since both calcium and magnesium are in group IIA they have two valence electrons, it means that the both of them have two electrons at their outer shells.

- They are highly soluble in water when forming ionic bonds with nonmetals such as those belonging to halogens and oxygen's family.

- Calcium has 18 electrons and magnesium 10 which are two less than the total protons (20 and 12 respectively) since the both of them have lost two electrons due their ionized form.

- Their electron configurations are:

Ca^{20}=1s^2,2s^2,2p^6,3s^3,3p^6,4s^2\\\\Mg^{12}=1s^2,2s^2,2p^6,3s^2

It means that the both of them are at the s region since it is the last subshell at which their electrons are.

Best regards.

8 0
4 years ago
1. What are the sources of water on Earth?
Lesechka [4]
Rivers, oceans, lakes, ponds
4 0
3 years ago
Read 2 more answers
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