Answer:
Choice B. The solid with hydrogen bonding.
Assumption: the molecules in the four choices are of similar sizes.
Explanation:
Molecules in a molecular solid are held intact with intermolecular forces. To melt the solid, it is necessary to overcome these forces. The stronger the intermolecular forces, the more energy will be required to overcome these attractions and melt the solid. That corresponds to a high melting point.
For molecules of similar sizes,
- The strength of hydrogen bonding will be stronger than the strength of dipole-dipole attractions.
- The strength of dipole-dipole attractions (also known as permanent dipole) will be stronger than the strength of the induced dipole attractions (also known as London Dispersion Forces.)
That is:
Strength of Hydrogen bond > Strength of Dipole-dipole attractions > Strength of Induced dipole attractions.
Accordingly,
Melting point due to Hydrogen bond > Melting point due to Dipole-dipole attractions > Melting point due to Induced Dipole attractions.
- Induced dipole is possible between all molecules.
- Dipole-dipole force is possible only between polar molecules.
- Hydrogen bonds are possible only in molecules that contain
atoms that are bonded directly to atoms of
,
, or
.
As a result, induced dipoles are the only force possible between molecules of the solid in choice C. Assume that the molecules are of similar sizes, such that the strengths of induced dipole are similar for these molecules.
Melting point in choice B > Melting point in choice D > Melting point in choice A and C.
Answer:
C. Its physical structures
Explanation:
A dichotomous key is defined as a tool used to differentiate between objects and organisms. A dichotomous key consist of series of question related to the species and at the end gives the scientific name of the species.
The characteristic that is most helpful when identifying organism using a dichotomous key is "Its physical structures". for example: if a person want to identify a tree, a dichotomous key ask about the physical structures such as if the tree has needles or leaves.
So, physical structures are most helpful while using a dichotomous key.
Steel is an alloy and consists of more than one element (mainly iron and carbon), therefore steel is a mixture.
Answer:
<h2>Volume = 57.34 dm³</h2>
Explanation:
The volume of a gas can be found by using the formula
V = n × V(dm³)
where
n is the number of miles
V is the volume
V(dm³) is the volume of 1 mole of a gas at STP which is 22.4 dm³
From the question
n = 2.56
The volume is
V = 2.56 × 22.4
We have the final answer as
<h3>Volume = 57.34 dm³</h3>
Hope this helps you
C - Negatively charged electrons orbit a positively charged nucleus