In the symbol 42he, the subscript 2 is the for helium and the superscript 4 is the for helium. question 10 options: atomic mass; atomic number atomic number; atomic mass mass number; atomic number atomic number; mass number

The correct answers for this problem is:

atomic number; atomic mass

Atomic number indicates the number of protons or electrons that is located in that atom. Helium contains 2 protons or electrons hence an atomic number of 2. Meanwhile the atomic mass of 4 indicates the mass of the atom per mole.

mass number; atomic number

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.