Explanation:
In gases the molecules are held together by weak Vander waal forces. Due to this they have more kinetic energy and they tend to diffuse at a faster rate because of more number of collisions between the molecules.
That is why, its molecules readily spread into the atmosphere as compared to the molecules of solids and liquids. Also, when molecules of a gas collide with the walls of a container then they tend to come back at their initial position for a fraction of second or more.
Hence, gas collisions are elastic in nature.
According to Graham's law, rate of diffusion of a gas is inversely proportional to the square root of molar mass of the gas. Hence, more is the molecular weight of gas less likely it is able to diffuse into the surroundings.

Thus, we can conclude that following apply to gases.
- Gas collisions are elastic.
- Gases mix faster than solids or liquids.
- Gases with larger molecular weights diffuse slower than gases with lower molecular weights.
B - The reactants are the starting substances and the products are the end substances.
Atomic radii increase when going down a group and decreases when going towards the anion periods. So A and D.
Answer:
a) 2-bromopyrrole
Explanation:
Our options for this questions are:
a) 2-bromopyrrole
b) 2,3-dibromopyrrole
c) N-bromopyrrole
d) 3-bromopyrrole
To understand how the reaction works we have to start with the <u>resonance structures</u>. (Figure 1), on these structures, we will obtain a n<u>egative charge on carbon 2</u> in the pyrrole ring, therefore on this carbon we can generate an attack to an electrophile.
The second step is to check how the mechanism take place. An <u>electrophile is generated</u> by the
and
. This electrophile can be <u>attacked</u> by the negative charge on carbon 2 producing the 2-bromopyrrole. (See figure 2).
I hope it helps!