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vlabodo [156]
2 years ago
10

How many days have passed if 4.80 mg of calcium-47 decayed to 1.2 mg of calcium-47?

Chemistry
1 answer:
LenaWriter [7]2 years ago
6 0
(1) 36 days is 8 half-life periods,
so 24mg becomes 24mg times (1/2)^8 = 24 mg/256 = 0.094 mg

(2) 9.6/1.2 = 8, which means three half-life periods went by.
At the end of 4.5 days, there were 4.8 mg
At the end of 9.0 days, there were 2.4 mg
At the end of 13.5 days, there were 1.2 mg

(3) The activity is proportional to the amount of radioactive material remaining,
so after two half-life periods, the activity should be 1/4 of what it originally was.
So the initial activity was probably 12.0 Ci
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A reaction mechanism has the following elementary step as the slow step: B2A What is the rate law for this elementary step? O ra
xenn [34]

Answer:

r = k [ B ]

Explanation:

  • B → 2A

⇒ r = k [ A ]/2 = k [ B ]

3 0
3 years ago
Why is the enzyme pectinase added during the manufacture of fruit juices?
MariettaO [177]
The choices can be found elsewhere and as follows:

<span>A.The enzyme pectinase speeds up the breakdown of pectin in fruits, producing more juice.. .
B.The enzyme pectinase enhances the taste of fruit juices, making them more popular.. .
C.The enzyme pectinase speeds up the breakdown of toxins in fruits, producing more juice.

The correct answer would be A. </span>The enzyme pectinase speeds up the breakdown of pectin in fruits, producing more juice. With this, the manufacturer company will get more volume of product from same amount of resource.
6 0
3 years ago
A ball-and-stick model of a molecule of formaldehyde, ch2o, is made from the following components: what do the sticks represent?
9966 [12]

In chemistry, the ball-and-stick model is a molecular ideal of a chemical matter which is to expose both the three-dimensional position of the atoms and the bonds among them. The atoms are normally symbolise by spheres, join by rods which shows the bonds.

Formaldehyde forms formaldehyde structure bond it shares double bond with O2 atoms.

Formaldehyde also known as methanol .

Methanol is colourless.

It is flammable.

It is gas at room temperature.

Methanol having pungent odor and it is a volatile organic compounds.

It is made by the composition of Hydrogen, oxygen, and carbons.

To know more about Formaldehyde here :

brainly.com/question/14895085?referrer=searchResults

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6 0
1 year ago
an atom has a charge of -3 in its orbitals which statement must be true in order for this atom to have no net charge
NISA [10]

Answer:

The atom must lose its three extra electrons to make the atom over all neutral.

Explanation:

The three subatomic particles construct an atom electron, proton and neutron. A neutral atom have equal number of proton and electron. In other words we can say that negative and positive charges are equal in magnitude and cancel the each other. For example if neutral atom has 6 protons than it must have 6 electrons.

If an atom have -3 charge it means three more electrons are added. In order to make the atom overall neutral three more electrons must be removed so that negative and positive charge becomes equal and cancel the effect of each other and make the atom neutral.

Electron:

The electron is subatomic particle that revolve around outside the nucleus and has negligible mass. It has a negative charge.

Symbol= e⁻

Mass= 9.10938356×10⁻³¹ Kg

It was discovered by j. j. Thomson in 1897 during the study of cathode ray properties.

Proton and neutron:

While neutron and proton are present inside the nucleus. Proton has positive charge while neutron is electrically neutral. Proton is discovered by Rutherford while neutron is discovered by James Chadwick in 1932.

Symbol of proton= P⁺

Symbol of neutron= n⁰

Mass of proton=1.672623×10⁻²⁷ Kg

Mass of neutron=1.674929×10⁻²⁷ Kg

7 0
3 years ago
What is the concentration of each ion in a solution that is prepared by dissolving 5.00 g of ammonium chloride in enough water t
const2013 [10]

Answer:

C = 0.08M

Explanation:

molar mass of AlCl3

Al =27

Cl = 35.5

27+3(35.5) =133.5g/mol

n= mass/Molar mass

n =CV

CV = mass/molar mass

C x 500 x 10^-³ = 5/133.5

C x 500 x 10^-³ = 0.04

C = 0.04/500 x 10^-³

C = 0.08M

4 0
3 years ago
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