The answer to the question is C
Answer:
- Nitrogen has four pairs of electrons: 3 bonds and 1 lone pair in the valence shell;
- Electrons repel one another based on the VSEPR theory;
- Nitrogen has a total of 7 protons (its atomic number is 7) in its nucleus.
Explanation:
The shape and the bond orientation of molecules and ions are both explained by the valences shell electron pair repulsion theory (VSEPR).
Ammonia,
, is a molecule which contains three N-H bonds, as well as one lone pair on nitrogen. According to the VSEPR theory, molecules try to acquire a shape which would minimize the repulsion exhibited by the electron clouds present, that is, between the bonding (shared in a bond) and non-bonding (lone pair) electrons.
In VSEPR, our main step is to calculate the steric number, this is the sum of the number of bonds (ignoring the multiplicity of any bond) and the lone pairs on a central atom. In ammonia, we have 3 bonds and 1 lone pair, totaling to a steric number of 4. A steric number of 4 without any lone pairs on a central atom and just bonds would yield a tetrahedral shape with bond angles of
.
Now, in this case, since we have a lone pair instead of a bond, it is repelling stronger decreasing the bond angles to about
.
The greater the number of lone pairs, the lower the angle becomes.
To summarize:
- Nitrogen has four pairs of electrons: 3 bonds and 1 lone pair in the valence shell;
- Electrons repel one another based on the VSEPR theory;
- Nitrogen has a total of 7 protons (its atomic number is 7) in its nucleus.
Answer:
The density of the metal is 0.561 g/mL
Explanation:
The computation of the density of the metal is shown below;
As we know that
The Density of the metal is

where,
Mass = 4.9g
Change in volume = 6.9 mL
Now place these values to the above formula
So, the density of the metal is

= 0.561 g/mL
Hence, the density of the metal is 0.561 g/mL
We simply applied the above formula so that the correct density could arrive
Answer:
1. 374.69 K
Explanation:
Hello,
In this case, pure water's boiling point is 373.15 K, thus by considering the boiling point increase equation:

Whereas i=2 since two ionic species are formed,actually, the experimental value is 2.42 so better work with it, thus:

Thus, the required boiling point is:

Regards.