All Free Chemistry MCQs with Answers

• A. 1s22s22p63s23p63d3
• B. 1s22s22p63s23p63d14s2
• C. 1s22s22p63s23p63d34s2
• D. 1s22s22p63s23p63d34p1

Explanation: The electronic configuration of an atom is determined by the Aufbau Principle, which states that electrons fill the lowest energy orbitals…

• A. -2
• B. -1
• C. +2
• D. +1

Explanation: The element with atomic number 19 is potassium (K) which is a group 1 metal. Hence it loses one electron to form the ion valence of K+1.

• A. N2
• B. O2
• C. F2
• D. He22+

Explanation: The correct answer is O2. According to molecular orbital theory, O2 has a configuration with two unpaired electrons in the π* 2p molecular…

• A. N2-
• B. Cl2-
• C. H2+
• D. O2

Explanation: To determine if a molecule has unpaired electrons in antibonding molecular orbitals, examine the molecular orbital diagrams.

• A. [Ar] 4S2 3d4
• B. [Ar] 4S0 3d10
• C. [Ar] 4S1 3d10
• D. [Ar] 4S2 3d7 4p2

Explanation: It is a transition element. Copper (Cu) is a chemical element, a reddish, extremely ductile metal of Group 11 (IB) of the periodic table…

• A. Option A
• B. Option B
• C. Option C
• D. Both option B and C are correct

Explanation: Options A and D are incorrect because two electrons with the same spin are not added to the same orbitals.

• A. I only
• B. I and III only
• C. I and II only
• D. II and III only

Explanation: The electron configuration for sodium (23Na) is correctly given as 1s22s22p63s1.

• A. D
• B. d-
• C. H-
• D. He

Explanation: H is Hydrogen, it's proton number is 1 so it has 1 proton, 1 electron and no neutrons.

• A. O2
• B. O+2
• C. O-2
• D. O2-2

Explanation: O2 has 2 unpaired electrons, O+2 has no unpaired electrons, O-2 has paired electrons while O2-2 also has no unpaired electrons hence the…

• A. Two
• B. One
• C. Zero
• D. None of the above

Explanation: The bond order for O2+2 is two, indicating a double bond.O2+2 is a diatomic molecule with two oxygen atoms.

• A. Lanthanides
• B. Transition elements
• C. Rate gases
• D. Actinides

Explanation: Actinides are a series of chemical elements that span from atomic number 89 (actinium) to 103 (lawrencium) on the periodic table.

• A. Scandium family
• B. Iron family
• C. Titanium family
• D. Beryllium family

Explanation: Beryllium (Be) and its family, which includes elements such as magnesium and calcium, are not transition metals.

• A. 2
• B. 3
• C. 4
• D. 5

Explanation: The charge on EN is 0. The charge on the water is 0, the charge on CN is -1, and the charge on the complex is +2.

• A. Zn2
• B. Cu2
• C. Fe
• D. Ba+2

Explanation: Reaction is CuSO4+2NH4OH----> (NH4)2SO4 +Cu(OH)2 The solution contains Cu2+ ions.

• A. red
• B. blue
• C. orange
• D. black

Explanation: Nickel bis(dimethyl glyoximate) is the coordination complex with a bright red colour.

• A. +2
• B. +5
• C. +7
• D. +8

Explanation: The highest oxidation state of manganese in its compounds is +7. In this oxidation state, manganese forms compounds like potassium…

• A. 1s2 2s2 2p6 3s2 3p6 3d8 4s2
• B. 1s2 2s2 2p6 3s2 3p6 3d7 4s2 4p1
• C. 1s2 2s2 2p6 3s2 3p6 3d6 4s2 4p2
• D. 1s2 2s2 2p6 3s2 3p6 3d6 4s1 4p3

Explanation: The correct electronic configuration for Nickel (28) is 1s2 2s2 2p6 3s2 3p6 3d8 4s2.

• A. Unpaired d Electrons
• B. Unpaired p electrons
• C. Unpaired f electrons
• D. Paired up d electrons

Explanation: Transition elements exhibit variable oxidation states due to the involvement of their ns and (n-1) d electrons.

• A. Two of its atoms
• B. Three of its atoms
• C. Four of its atoms
• D. Six of its atoms

Explanation: When this ion bonds to a metal atom, the two N atoms, and four of the O atoms, are used.

• A. Open hearth furnace
• B. Reverberatory furnace
• C. Bessemer converter
• D. Blast furnace

Explanation: A puddling furnace is used which is a type of an open hearth furnace, it is constructed to pull hot air over the iron without the fuel…