Answer:
a
The condensed structural formula for methane is
b
The condensed structural formula for ethane is
c
The condensed structural formula for pentane is
d
The diagram for the structural formula for cyclopropane is shown on the first uploaded image
Explanation:
The most stable conformation of 3-isopropyl-1,1dimethylcyclohexane equatorial ethyl group (more stable). The stability of ethylcyclohexane's equatorial conformer exceeds that of its axial conformer by 7.4 kJ/mol.
According to the previous section, the chair conformation with the equatorial methyl group is more stable because it reduces steric repulsion, and as a result, the equilibrium favors the more stable conformer. Strongly favoring the equatorial shape is methylcyclohexane. The methyl group is in close proximity to the axial hydrogens in the axial conformation, which has an energetically unfavorable effect known as a 1,3-diaxial interaction. The methyl group prefers the equatorial shape as a result. The conformation of ethylcyclohexane in which the ethyl group is in the equatorial position is the most stable.
Learn more about equatorial ethyl group here:
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Answer:
Approximately 75%.
Explanation:
Look up the relative atomic mass of Ca on a modern periodic table:
There are one mole of Ca atoms in each mole of CaCO₃ formula unit.
Calculate the mass ratio of Ca in a pure sample of CaCO₃:
.
Let the mass of the sample be 100 g. This sample of CaCO₃ contains 30% Ca by mass. In that 100 grams of this sample, there would be of Ca atoms. Assuming that the impurity does not contain any Ca. In other words, all these Ca atoms belong to CaCO₃. Apply the ratio
:
.
In other words, by these assumptions, 100 grams of this sample would contain 75 grams of CaCO₃. The percentage mass of CaCO₃ in this sample would thus be equal to:
.