if 20.g of a radioactive isotope are present at 1:00 pm and 5.0g remain at 2:00 pm, what is the half life of the isotope?

1 answer:

4 0

The half life of the isotope is calculated as follows

the time difference = 2.00- 1.00 = 1 hour(60min)

if 20 g decay in 1 hour (60min) and 5 grams remains then the mass that decay = 20-5 = 15 grams

the half life is time required for a quantity to reduce to half its initial value

and if the initial concentration = 20g then the half = 20/2 = 10g

then time = 10g x 60min/15g = 40 min

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The volume of distilled water that should be added to 10.0 mL of 6.00 M HCl(aq) in order to prepare a 0.500 M HCl(aq) solution i

bija089 [108]

Answer:

110ml

Explanation:

Using the dilution equation, C1V1 = C2V2

Where C1 is the initial concentration of solution

C2 is final concentration of solution

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V2 is final volume of solution.

From the question , C1=6M, C2=0.5M, V1=10ml, V2=?

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Answer:

four (4)

Explanation:

Naphthalein is an organic compound with formula C 10H 8. It is the simplest polycyclic aromatic hydrocarbon, and is a white crystalline solid with a characteristic odor that is detectable at concentrations as low as 0.08 ppm by mass. As an aromatic hydrocarbon, naphthalene's structure consists of a fused pair of benzene rings. It is best known as the main ingredient of traditional mothballs.

The molecule is planar, like benzene. Unlike benzene, the carbon–carbon bonds in naphthalene are not of the same length. The bonds C1−C2, C3−C4, C5−C6 and C7−C8 are about 1.37 Å (137 pm) in length, whereas the other carbon–carbon bonds are about 1.42 Å (142 pm) long. This difference, established by X-ray diffraction is consistent with the valence bond model in naphthalene and in particular, with the theorem of cross-conjugation. This theorem would describe naphthalene as an aromatic benzene unit bonded to a diene but not extensively conjugated to it (at least in the ground state), which is consistent with two of its three resonance structures.

Because of this resonance, the molecule has bilateral symmetry across the plane of the shared carbon pair, as well as across the plane that bisects bonds C2-C3 and C6-C7, and across the plane of the carbon atoms. Thus there are two sets of equivalent hydrogen atoms: the alpha positions, numbered 1, 4, 5, and 8, and the beta positions, 2, 3, 6, and 7. Two isomers are then possible for mono-substituted naphthalenes, corresponding to substitution at an alpha or beta position. Bicyclo[6.2.0]decapentaene is a structural isomer with a fused 4–8 ring system.

Therefore four (4) double bonds will be added to give each carbon atom an octet structure.