D) refracted
because , the light changes direction.. causing the penny to look bigger than it is.
Answer:
The molar mass of a substance is defined as the mass in grams of 1 mole of that substance. One mole of isotopically pure carbon-12 has a mass of 12 g. ... That is, the molar mass of a substance is the mass (in grams per mole) of 6.022 × 1023 atoms, molecules, or formula units of that substance.
Explanation:
It would take 147 hours for 320 g of the sample to decay to 2.5 grams from the information provided.
Radioactivity refers to the decay of a nucleus leading to the spontaneous emission of radiation. The half life of a radioactive nucleus refers to the time required for the nucleus to decay to half of its initial amount.
Looking at the table, we can see that the initial mass of radioactive material present is 186 grams, within 21 hours, the radioactive substance decayed to half of its initial mass (93 g). Hence, the half life is 21 hours.
Using the formula;
k = 0.693/t1/2
k = 0.693/21 hours = 0.033 hr-1
Using;
N=Noe^-kt
N = mass of radioactive sample at time t
No = mass of radioactive sample initially present
k = decay constant
t = time taken
Substituting values;
2.5/320= e^- 0.033 t
0.0078 = e^- 0.033 t
ln (0.0078) = 0.033 t
t = ln (0.0078)/-0.033
t = 147 hours
Learn more: brainly.com/question/6111443
Branched chain alkanes
The alkanes don't contain a functional group and so the branches are numbered from the end that gives the lowest set of position numbers for the branches.
Use the above rules to see how the names of the alkanes below are built up.
The structure of 2-methylbutane is a butane molecule (C4H10) but with a methyl group (CH3) replacing a hydrogen on the second carbon atom in the chain. The structure of 3-methylpentane could be drawn as butane with an ethyl group (C2H5) replacing a hydrogen on the second carbon. Note that this is not 2-ethylbutane. The structure of 2,2-dimethylbutane is butane with two methyl groups replacing the two hydrogens on the second carbon.
