There are two important isotopes of uranium— 235u and 238u; these isotopes are nearly identical chemically but have different atomic masses. only 235u is very useful in nuclear reactors. one of the techniques for separating them (gas diffusion) is based on the different average velocities vrms of uranium hexafluoride gas, uf6. (a) the molecular masses for 235uuf6 and 238uuf6 are 349.0 g/mol and 352.0 g/mol, respectively. what is the ratio of their average velocities?

1.0043

Explanation:

The formula for root mean square velocity is:

Where,

R is the universal gas constant

T is the temperature

M is the molecular weight

Since, seen from the formula, root mean square velocity is inversely proportional to the square root of the molecular mass.

Thus, for two gases like .The expression is:

The molecular mass of is 349.0 g/mol

The molecular mass of is 352.0 g/mol

substituting a hydrogen atom with a halogen in a hydrocarbon:

- the single bond remains single. a is wrong.

- the bond with hydrogen is as strong as with a halogen. c is wrong

- a hydrocarbon is saturated if there is no double bond. we do not know that so d is wrong.

- carbon will always have four valence electrons. e is wrong.

by elimination, the correct answer is b. the boiling point of the new compound increases.

nuclear fission produces elements that are heavier than helium.

the elements that are used in nuclear fission and their products are much heavier than helium.