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scZoUnD [109]
3 years ago
7

What is the half-life of a 12 g sample of radioisotope that decayed to 6 g in 28

Chemistry
1 answer:
Charra [1.4K]3 years ago
4 0

Answer:

A. 28 years

Explanation:

Applying,

R = R'(2ᵃ/ⁿ).............. Equation 1

Where R = Original sample, R' = Sample left after decay, a = Total time taken to decay, n = half life.

From the question,

Given: R = 12 g, R' = 6 g, a = 28 years.

Substitute into equation 1 and solve for n

12 = 6(2²⁸/ⁿ)

12/6 = 2²⁸/ⁿ

2²⁸/ⁿ = 2

Equation the base,

28/n = 1

n = 28 years.

Hence the half-life is 28 years

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The intermolecular forces present in CH 3NH 2 include which of the following? I. dipole-dipole II. ion-dipole III. dispersion IV
astra-53 [7]

Answer:

I. dipole-dipole

III. dispersion

IV. hydrogen bonding

Explanation:

Intermolecular forces are weak attraction force joining nonpolar and polar molecules together.

London Dispersion Forces are weak attraction force joining non-polar and polar molecules together. e.g O₂, H₂,N₂,Cl₂ and noble gases. The attractions here can be attributed to the fact that a non -polar molecule sometimes becomes polar because the constant motion of its electrons may lead to an uneven charge distribution at an instant.

Dispersion forces are the weakest of all electrical forces that act between atoms and molecules. The force is responsible for liquefaction or solidification of non-polar substances such as noble gas an halogen at low temperatures.

Dipole-Dipole Attractions are forces of attraction existing between polar molecules ( unsymmetrical molecules) i.e molecules that have permanent dipoles such as HCl, CH3NH2 . Such molecules line up such that the positive pole of one molecule attracts the negative pole of another.

Dipole - Dipole attractions are more stronger than the London dispersion forces but weaker than the attraction between full charges carried by ions in ionic crystal lattice.

Hydrogen Bonding is a dipole-dipole intermolecular attraction which occurs when hydrogen is covalently bonded to highly electronegative elements such as nitrogen, oxygen or fluorine. The highly electronegative elements have very strong affinity for electrons. Hence, they attracts the shared pair of electrons in the covalent bonds towards themselves, leaving a partial positive charge on the hydrogen atom and a partial negative charge on the electronegative atom ( nitrogen in the case of CH3NH2 ) . This attractive force is know as hydrogen bonding.

7 0
3 years ago
Iron filings were mixed together with salt crystals. What unique property of iron would be BEST to separate the filings from the
Sedaia [141]
Iron has magnetic properties, so you would just need to hold a magnet over the mixture and the filings will come right out.
4 0
3 years ago
Read 2 more answers
A quantity of NaCl was dissolved in 100 cm of solution to obtain
soldi70 [24.7K]

Answer:

2.93g

Explanation:first, let us calculate the number of mole of NaCl present in the solution. This is illustrated below:

Molarity = 0.5M

Volume = 100cm^3 = 100/1000 = 0.1L

Mole =?

Molarity = mole /Volume

Mole = Molarity x Volume

Mole of NaCl = 0.5 x 0.1 = 0.05mole

Now we can obtain the mass of NaCl as follows:

Molar Mass of NaCl = 23 + 35.5 = 58.5g/mol

Mole of NaCl = 0.05mol

Mass of NaCl =?

Mass = number of mole x molar Mass

Mass of NaCl = 0.05 x 58.5

Mass of NaCl = 2.93g

7 0
4 years ago
Need help please help
zimovet [89]

Explanation:

a)phenotype= 100% big

b) genotype=1:2:1 (FF-25%, Ff-50%, ff-25%)

phenotype=3:1 (big=75%, small= 25%)

7 0
3 years ago
Lithium diorganocopper (Gilman) reagents are prepared by treatment of an organolithium compound with copper(I) iodide. Decide wh
Ann [662]

Answer:

See explanation and image attached

Explanation:

The  Gilman reagent is a lithium and copper (diorganocopper) reagent with a general formula R2CuLi.  R is an alkyl or aryl group.

They are useful in the synthesis of alkanes because they react with organic halides to replace the halide group with an R group.

In this particular instance, we intend to synthesize propylcyclohexane. The structure of the  lithium diorganocopper (Gilman) reagent required is shown in the image attached to this answer.

7 0
3 years ago
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