FBISE Class 9th (SSC-l)
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Total MCQs
FBISE Class 9th (SSC-l)
Answer: Atomic size decreases across a period from left to right due to increasing effective nuclear charge pulling electrons closer to the nucleus.
Answer: Ca(OH)2 has n-factor = 2 (two OH- groups). Equivalent weight = 74 / 2 = 37 g/mol.
Answer: Al(OH)3 is amphoteric: it reacts with both acids (forming Al3+ salts) and bases (forming aluminate ions).
Answer: At 443 K (high temperature), ethanol undergoes dehydration to form ethene (CH2=CH2) and water via elimination of OH and H from adjacent carbons.
Answer: FCC has 8 corner atoms (8 x 1/8 = 1) + 6 face atoms (6 x 1/2 = 3) = 4 atoms per unit cell.
Answer: MgO has the highest lattice energy due to the small ionic radii and high charges (+2 and -2) of Mg2+ and O2-, resulting in very strong electrostatic attractions.
Answer: In Fe2O3: 2(Fe) + 3(-2) = 0, so 2Fe = 6, Fe = +3.
Answer: Ethyne (acetylene, C2H2) contains a carbon-carbon triple bond (C≡C), making it an alkyne.
Answer: MnO2 oxidizes HCl to produce Cl2: MnO2 + 4HCl -> MnCl2 + Cl2 + 2H2O. Here MnO2 is the oxidizing agent.
Answer: Propanone has the structure CH3COCH3. The carbonyl group is at carbon 2, so its IUPAC name is propan-2-one (commonly called acetone).
Answer: Primary alkyl halides favor SN2 because they have minimal steric hindrance, and strong nucleophiles with polar aprotic solvents further promote bimolecular substitution.
Answer: As Q increases, the logarithmic term (RT/nF)lnQ becomes more positive, which reduces E from E0, decreasing the cell potential.
Answer: At constant pressure, q = Delta H. Since heat is released (exothermic), Delta H = -200 J by sign convention.
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Answer: Rate = k[A]^n. If 2^n = 4, then n = 2, meaning the reaction is second order with respect to A.
Answer: CN- is a strong field ligand at the top of the spectrochemical series, causing the largest crystal field splitting (Delta_o).
Answer: SN1 proceeds through a planar carbocation intermediate. Nucleophilic attack from both faces gives racemization, but ion pairing often causes slight excess inversion.
Answer: SN2 is bimolecular: both the substrate and nucleophile are involved in the rate-determining step, so Rate = k[CH3Br][OH-].
Answer: Six NH3 ligands give coordination number 6. Each NH3 is neutral and 3 Cl- balance the charge, so Co is +3.
Answer: The complex can exist as cis (Cl ligands adjacent) and trans (Cl ligands opposite) geometric isomers due to its octahedral geometry.
Answer: Hess\'s law states that the total enthalpy change for a reaction is the same regardless of whether it occurs in one step or multiple steps, because enthalpy is a state function.