Select the atomic models that belong to the same element.

Left Panel

The trick is to look at the protons, all other things being equal. The yellow spheres are neutrons we are led to believe. All the diagrams show the same number of electrons(2), so there is no help there.

The upper left

The upper right

The Lower left

All have 2 protons and 2 electrons. <<<< Answer Read the 3 lines above.  

The center one has only 1 proton And the lower right has 3. Both of them are wrong.

Right Panel

You have answered this one correctly

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.

answerlinnaeus;