All categories

3 years ago

One hundred million copper atoms are arranged in a line. Which is a reasonable estimate for the length of this line?

1 answer:

8 0

The size of an atom is roughly 10^-10 metres

10^-10 • 100,000,000 = 0.01 metres

Since 1 metre = 100 centimetre

0.01 x 100 = 1 centimetre

There’s your answer

You might be interested in

An isotope of cesium-137 has a half-life of 30 years. If 5.0g of cesium-137 decays over 60 years. How many grams will remain.

LenKa [72]

Answer:

1.25 gram of cesium-137 will remain.

Explanation:

Given data:

Half life of cesium-137 = 30 year

Mass of cesium-137 = 5.0 g

Mass remain after 60 years = ?

Solution:

Number of half lives passed = Time elapsed / half life

Number of half lives passed = 60 year / 30 year

Number of half lives passed = 2

At time zero = 5.0 g

At first half life = 5.0 g/2 = 2.5 g

At 2nd half life = 2.5 g/ 2 = 1.25 g

Thus. 1.25 gram of cesium-137 will remain.

6 0

2 years ago

Do protons determine isotopes

Bezzdna [24]

Answer:

Explanation:

Protons determine the type of element it is which the number of protons.

Isotopes are determined by the same elements with the same amount of protons, but different number of neutrons.

5 0

3 years ago

A particular voltaic cell operates with the reaction: Zn(s)+Cl2(g)--->Zn^2+(aq)+2Cl^-(aq) giving a cell potential of .853 V.

nadya68 [22]

Answer:

The amount of energy liberated will be 49.38 J.

Explanation:

The amount of energy liberated (gibbs free energy) can be calculated using the following equation:

ΔG° = -nFε

n: amount of moles of electrons transfered

F: Faraday's constant

ε: cell potential

20.0 g of Zn is equal to 0.30 mol.

Two electrons are transfered during the reaction.

Therefore, n = 2x0.30 ∴ n = 0.60

ΔG° = - 0.60 x 96.485 x 0.853

ΔG° = 49.38 J

3 0

3 years ago

How do you know a physical change has occurred when evaporating water produces gaseous water?

levacccp [35]

Answer:

Its b its the state not anything else

6 0

2 years ago

The half-life for beta decay of strontium-90 is 28.8 years. a milk sample is found to contain 10.3 ppm strontium-90. how many ye

ryzh [129]

Answer : The correct answer is 96.68 yrs

Radioactivity Decay :

it is a process in which a nucleus of unstable atom emit energy in form of radiations like alpha particle , beta particle etc .

Radioactive decay follows first order kinetics , so its rate , rate constant , amount o isotopes can be calculated using first order equations .

The first order equation for radioactive decay can be expressed as :

$ln \frac{N}{N_0} = - k*t$ ----------- equation (1)

Where : N = amount of radioisotope after time "t"

N₀ = Initial amount of radioisotope

k = decay constant and t = time

Following steps can be used to find time :

1) To find deacy constant :

Decay constant can be calculated using half life . Decay constant and half life can be related as :

$T _\frac{1}{2} = \frac{ln2}{k}$ ---------equation (2)

Given : Half life of Strontium -90 = 28.8 years

Plugging value of $T_\frac{1}{2}$ in above formula (equation 2) :

$28.8 yrs = \frac{ln 2}{ k }$

Multiply both side by k

$28.8 yrs * k = \frac{ln 2 }{k} * k$

Dividing both side by 28.8 yrs

$\frac{28.8 yrs * k}{28.8 yrs} = \frac{ln 2}{28.8 yrs}$

(ln 2 = 0.693 )

k = 0.0241 yrs⁻¹

Step 2 : To find time :

Given : N₀ = 10.3 ppm N = 1.0 ppm k = 0.0241 yrs⁻¹

Plugging these value in equation (1) as :

$ln (\frac{1.0 ppm}{10.3 ppm} ) = - 0.0241 yrs^-^1 * t$

$ln (0.0971 ) = -0.0241 yrs ^-^1 * t$

(ln 0.0971 = - 2.33 )

Dividing both side by - 0.0241 yrs⁻¹

$\frac{-2.33}{-0.0241 yrs^-^1} = \frac{-0.0241 yrs^-^1 * t}{-0.0241 yrs^-^1}$

t = 96.68 yrs

Hence the concentration of Strontium-90 will drop from 10.3 ppm to 1.0 ppm is 96.68 yrs

3 0

3 years ago

Read 2 more answers