Chemistry Revision Questions and Answers

Revision Questions

Electronic Configuration

Question 1: Electronic configuration of Neon (Ne, atomic number 10) in terms of subshells.
- $1s^22s^22p^6$
Question 2: Electronic configuration of Sodium (Na) in extended form and noble gas notation.
- Extended form: $1s^22s^22p^63s^1$
- Noble gas notation: $[Ne]3s^1$

Ionic Bonds

Question 3: Calcium oxide (CaO) ionic bond example.
- Calcium (Ca): $1s^22s^22p^63s^23p^64s^2$
- Oxygen (O): $1s^22s^22p^4$
- CaO is an example of an ionic bond because:
  - Ca loses 2 electrons to become $Ca^{2+}$ .
  - O gains 2 electrons to become $O^{2-}$ .
  - The electrostatic attraction between $Ca^{2+}$ and O^{2-}$ creates an ionic bond.

Electronegativity

Question 4: Highest electronegativity among Hydrogen (H), Fluorine (F), and Boron (B).
- Fluorine (F) has the highest electronegativity.

Covalent Bonds

Question 5: Covalent bond between atoms with the same electronegativity.
- Non-polar covalent bond.
Question 6: Is H_2 $an example of an ionic or covalent bond? <ul> <li>Covalent bond.</li></ul></li> </ul> <h4 id="reactiontypes">Reaction Types</h4> <ul> <li>Question 7: Reaction type for$ AB + CD \rightarrow AD + CB $. <ul> <li>Double displacement.</li></ul></li> <li>Question 8: Reaction type for$ NH4OH + HBr \rightarrow H2O + NH_4Br $. <ul> <li>Acid-Base.</li></ul></li> <li>Question 9: Identify an acid according to Arrhenius. <ul> <li>$ H2SO4 $<ul> <li>Arrhenius acids produce$ H^+ $ions in aqueous solution.</li></ul></li></ul></li> </ul> <h4 id="organicchemistry">Organic Chemistry</h4> <ul> <li>Question 10: Carbon's tetravalency. <ul> <li>It always forms 4 covalent bonds.</li></ul></li> <li>Question 11: Condition for hydrocarbons to be isomers. <ul> <li>They have the same "Brutto" (molecular) formula but different structural expressions.</li></ul></li> </ul> <h4 id="statesofmatter">States of Matter</h4> <ul> <li>Question 12: State transition from solid to gas. <ul> <li>Sublimation.</li></ul></li> <li>Question 13: Boiling point of linear octane vs. its isomers. <ul> <li>Linear octane has a higher boiling point due to greater surface area and stronger Van der Waals forces.</li></ul></li> <li>Question 14: Incorrect statement about alkynes. <ul> <li>Their structure is always planar (This is incorrect).</li> <li>Correct statements about Alkynes:<ul> <li>In the chain there are always two Carbon atoms bonded with a triple bond</li> <li>They are all non-saturated hydrocarbons</li> <li>Their general formula is$ CnH{2n-2} $</li></ul></li></ul></li> </ul> <h4 id="ionsandbonding">Ions and Bonding</h4> <ul> <li>Question 15: Definition of an ion. <ul> <li>An atom which has gained/lost electrons.</li></ul></li> <li>Question 16: Hydrogen bond formation. <ul> <li>Molecules where the hydrogen atom is bonded to a more electronegative atom (e.g., O, N, F).</li></ul></li> <li>Question 17: Number of atoms in compounds. <ul> <li>$ Al2(SO4)_3 = 2Al + 3S + 12O = 17 $</li> <li>$ K2SO3 = 2K + S + 3O = 6 $</li> <li>$ Mg(OH)_2 = Mg + 2O + 2H = 5 $</li> <li>$ AlK(SO4)2 = Al + K + 2S + 8O = 12 $</li> <li>$ K3Fe(CN)6 = 3K + Fe + 6C + 6N = 16 $</li></ul></li> <li>Question 18: "Brutto" formula of$ SiH_4 $. <ul> <li>$ SiH_4 $</li></ul></li> <li>Question 19: Boiling point difference between 1-pentanol and hexane. <ul> <li>The intermolecular forces in alcohols are greater than those in hydrocarbons due to hydrogen bonding.</li></ul></li> </ul> Note: The visual representations of the molecules associated with this question are not representable with text. <ul> <li>Question 20: Type of Alcohol<ul> <li>Tertiary</li></ul></li> </ul> Note: Picture required <ul> <li>Question 21: How are these molecules called? Which is their primary use in Organic Chemistry?<ul> <li>Amines, as catalyst</li></ul></li> </ul> Note: Picture required <ul> <li>Question 22: Identify if the following is a cis- or trans- compound<ul> <li>Trans</li></ul></li> </ul> Note: Picture required <ul> <li>Question 23: Fill in the blanks <ul> <li>Structural isomers are identical in chemical composition but differ structurally</li> <li>The primary source of energy for all mammals is glucose, a simple sugar</li></ul></li> <li>Question 24: How are these two molecules classified? <ul> <li>Enantiomers</li></ul></li> </ul> Note: Picture required <ul> <li>Question 25: How many stereoisomers would Tetrose make? Why?<ul> <li>Tetrose would make 4 stereoisomers</li></ul></li> </ul> <h4 id="structuresquestions">Structures Questions</h4> <ul> <li>Question 26: What is its “Brutto Formula”?<ul> <li>$ C6H{12} $</li></ul></li> </ul> Note: Picture required <ul> <li>Question 27: Which one is not an isomer of the others?<ul> <li>CH3 CH2 CH2 CH CH3 (CH3 is attached to the last CH)</li></ul></li> </ul> Note: Picture required <ul> <li>Question 28: How many Hydrogen atoms are in the Alkane group Butane both in the linear and cyclical form? (Draw the molecules and count the H atoms) <ul> <li>Linear: 10</li> <li>Cyclical: 8</li></ul></li> <li>Question 29: Which compound among these contains the largest number of Hydrogen atoms?</li> </ul> Note: Picture required <ul> <li>Question 30: A student wrote the formula of 2-hexene in the following way. What is the error?</li> </ul> Note: Picture required <ul> <li>Question 31: Which one is the formula of 2-butene?</li> </ul> Note: Picture required <ul> <li>Question 32: Given the following sugar, identify how many chiral centres it contains:<ul> <li>0</li></ul></li> </ul> Note: Picture required <ul> <li>Question 33: Balance the following equations:<ul> <li>$ K2SO4 + Ba(OH)2 \rightarrow BaSO4 + 2KOH $</li> <li>$ CaCO3 + 2HCl \rightarrow CaCl2 + H2CO3 $</li> <li>$ BaSO_4 + 4C \rightarrow BaS + 4CO $</li> <li>$ Zn + I2 \rightarrow ZnI2 $</li> <li>$ 2SnCl2 + 2HgCl2 \rightarrow 2SnCl4 + Hg2Cl_2 $</li> <li>$ Zn + 2HCl \rightarrow ZnCl2 + H2 $</li> <li>$ Al2O3 + 3H2SO4 \rightarrow Al2(SO4)3 + 3H2O $</li> <li>$ 2H3PO4 + 3Ca(OH)2 \rightarrow Ca3(PO4)2+ 6H_2O $</li> <li>$ 3CaCl2 + 2Na3PO4 \rightarrow Ca3(PO4)2 + 6NaCl$$