Sorry, that is incorrect.

The only correct answer is: ions

• only carbocations is not correct because both anions and cations are produced
• only free radicals is not correct because homolytic fission produces free radicals
• free radicals and ions is not correct because homolytic fission produces free radicals and heterolytic fission also produces anions

Sorry, that is incorrect.

The only correct answer is: 503 , 965 , 3458 , 4530

• 1000 , 2251 , 3361 , 4564 is not correct because there is no significant rise from the second to the third IE. Therefore, it is not a Group 2 element.
• 496 , 4563 , 6913 , 9544 is not correct because there is a significant rise between the first and second IEs, indicating a Group 1 element.
• 578 , 1817 , 2745 , 11578 is not correct because there is a significant rise from the third to the fourth IE, indicating a Group 3 element.

Sorry, that is incorrect.

The only correct answer is: 8 protons, 10 neutrons, and 8 electrons

• 9 protons, 9 neutrons, and 9 electrons is incorrect because oxygen atoms do not have this number of protons.
• 0 protons, 8 neutrons, and 10 electrons is incorrect because oxygen atoms do not have this number of protons.
• 18 protons, 18 neutrons, and 18 electrons is incorrect because oxygen atoms do not have this number of protons.

Sorry, that is incorrect.

The only correct answer is: 12 

• 5 is incorrect because this is the number of electrons in the 3p orbitals of the chlorine atom
• 6 is incorrect because this is only the number of electrons in the 3p orbitals of the chloride ion
• 18 is incorrect because this is the total number of electrons in the chloride ion, not just those in the p orbitals.

Sorry, that is incorrect.

The only correct answer is: $Br^{+}_{(g)}-e^{-} \longrightarrow Br^{2+}_{(g)}$

• $Br_{(g)}+e^{-} \longrightarrow Br^{-}_{(g)}$ is incorrect because it is the equation for first electron affinity.
• $Br^{-}_{(g)}+e^{-} \longrightarrow Br^{2-}_{(g)}$ is incorrect because it is the equation for second electron affinity.
• $Br_{(g)}-2e^{-} \longrightarrow Br^{2+}_{(g)}$ is incorrect because it is an equation that combines both first and second ionization.

Sorry, that is incorrect.

The only correct answer is: 801 , 2427 , 3660 , 25,026

• 1086 , 2353 , 4621 , 6223 is incorrect because this does not show a large increase for the fourth ionization, so it is not in group 3.
• 900 , 1757 , 14,849 , 21,007 is incorrect because it shows a large increase for the third ionization, so it is in group 2.
• 578 , 1817 , 2745 , 11,578 is incorrect because it is a group 3 element as it has a large increase for the fourth ionization, but it has a first ionization energy that is lower than that of the correct option. So it is below it in Group 3. So it cannot be Boron.

Sorry, that is incorrect.

The only correct answer is: $1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p6$

• $1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{2}$ is incorrect because two electrons have been removed instead of added to the sulfur atom.
• $1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{4}$ is incorrect because this is the electronic configuration of the sulfur atom.
• $1s^{2} 2s^{2} 2p^{6} 3p^{6}$ is incorrect because this is the incorrect electronic configuration of the sulfur atom.

Sorry, that is incorrect.

The only correct answer is: 801 , 2,427 , 3,660 , 25,026 , 32,828

• 738 , 1,451 , 7,733 , 10,541 , 13,629 is incorrect because it is typical of group 2 elements.
• 1,086 , 2,353 , 4,621 , 6,223 , 37 832 is incorrect because it is typical of group 4 elements.
• 1,402 , 2,856 , 4,578 , 7,475 , 9 445 is incorrect because it could be for group 5,6,7,8 or transition elements.

Sorry, that is incorrect.

The only correct answer is: Fluoromethane ($CH_{2}F$)

• Hydrogen fluoride (HF) is not correct because fluorine is very electronegative and has a suitable lone pair of electrons for hydrogen bonding.
• Hydrogen peroxide ($H_{2}O_{2}$) is not correct because it has hydrogen bonding; compare with water.
• Methanol ($CH_{2}OH$) is not correct because alcohols can have hydrogen bonds; compare with water.

Sorry, that is incorrect.

The only correct answer is: $CO_{2}$

• $H_{2}S$ is not correct because it has a similar shape to water.
• $SO_{2}$ is not correct because it has a trigonal planar shape, resulting from the lone pair and two groups of electrons in the two double bonds.
• $CH_{2} = CH_{2}$ is not correct because it is planar but not linear.