Answer:
The correct option is;
It is always necessary to include a Roman numeral after the symbol of the metal
Explanation:
The transition metals can form ionic compounds with other elements by giving different number of electrons such that the transition metals can combine to form compounds in which they have different oxidation states
Therefore, in a compound formed by a transition metal, the value of the transition metal's valency or oxidation state in the compound is indicated by the inclusion of an equivalent Roman numeral after the transition metal in the name of the chemical formula of the compound
Crystallization produces heat.
<u>Answer:</u>
<u>For A:</u> The average molecular speed of Ne gas is 553 m/s at the same temperature.
<u>For B:</u> The rate of effusion of
gas is 
<u>Explanation:</u>
<u>For A:</u>
The average molecular speed of the gas is calculated by using the formula:

OR

where, M is the molar mass of gas
Forming an equation for the two gases:
.....(1)
Given values:

Plugging values in equation 1:

Hence, the average molecular speed of Ne gas is 553 m/s at the same temperature.
<u>For B:</u>
Graham's law states that the rate of diffusion of a gas is inversely proportional to the square root of the molar mass of the gas. The equation for this follows:

Where, M is the molar mass of the gas
Forming an equation for the two gases:
.....(2)
Given values:

Plugging values in equation 2:

Hence, the rate of effusion of
gas is 