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Questions and Answers
How many significant figures does 2.0034 have?
Molality is defined as the number of moles of solute present in which of the following?
What did Dalton propose about atoms?
What is the SI unit of density?
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What factor does the mass of a positively charged particle depend on?
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Which series of transitions in the hydrogen atom spectrum falls in the visible region?
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How can the electronic configuration of calcium (Z = 20) correctly be written?
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Mendeleev's periodic classification was based on which of the following?
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What is the empirical formula for a compound containing 26.67% carbon, 2.22% hydrogen, and 71.11% oxygen with a molar mass of 90 g mol-1?
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Which type of hybridization is present in the carbon atom of the compound H3C-CH2-CH=CH-CHO?
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What is a characteristic feature of aliphatic compounds?
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Which of the following best describes homolytic cleavage?
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In which order are the stability of carbocations ranked from least to most stable?
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What method is used to estimate halogen content in a compound?
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What is the wavelength of radiation broadcasted by Vividh Bharati station at a frequency of 1368 Hz?
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What is the energy of one mole of photons for radiation with a frequency of 5 x 10^14 Hz?
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Which of the following is non-polar in nature?
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What is the correct order of extent of repulsion among bond pairs and lone pairs?
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Which statement regarding bond enthalpy is correct?
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Which property of carbon is crucial for forming a large number of carbon compounds?
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Pent-2-ene contains how many sigma and pi bonds?
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When is fractional distillation employed?
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What is a polar covalent bond?
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Which is a characteristic of cathode rays?
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What does Pauli's exclusion principle state?
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Which of the following correctly defines isoelectronic species?
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Study Notes
Chemistry P.U.C. First Year Midterm Exam Notes
Part A: Multiple Choice Questions
- Non-polar molecule: CO2 is non-polar due to symmetrical linear structure.
- Order of repulsion: Lone pair-lone pair > lone pair-bond pair > bond pair-bond pair.
- Bond enthalpy definition: Energy required to break one mole of a bond in gaseous state.
- Carbon's properties: Catenation, isomerism, and tetravalency contribute to extensive carbon compound formation.
- Pent-2-ene consists of 14 sigma bonds and one pi bond.
- IUPAC naming options for organic compounds highlight practicality in nomenclature.
- Fractional distillation is applicable when there's a small difference in boiling points of liquids.
Part B: Short Answer Questions
- Law of multiple proportions: Different compounds formed from the same elements combine in ratios of small whole numbers.
- Pauli's exclusion principle: No two electrons in an atom can have the same set of four quantum numbers.
- Isoelectronic species: Atoms or ions with the same number of electrons; examples include Ne and F⁻.
- Elements with Z = 14 are situated in Period 3, Group 14 of the periodic table.
- Lewis symbols represent valence electrons, crucial for bonding information (O has 6, CO2 shows C=O double bonds).
- Polar covalent bond: Results from unequal sharing of electrons; example: HCl.
- Inductive effect involves electronic shifts through sigma bonds; resonance effect involves delocalization of electrons across multiple adjacent atoms.
Part C: Detailed Answers
- Ionization enthalpy decreases down a group due to increasing atomic size which reduces nuclear attraction.
- Na+ is smaller than Na because it loses a valence electron, reducing electron-electron repulsion.
- IUPAC name for element with atomic number 110 is Darmstadtium (Ds).
- Water molecule shape is bent according to VSEPR theory due to two lone pairs on oxygen influencing bond angles.
- Sigma bonds are formed by head-on overlap of orbitals while pi bonds form by side-to-side overlap.
Part D: Extended Answers
- Heterogeneous mixture consists of visibly different substances; example: salad.
- Scientific notation for 0.0048 is expressed as 4.8 x 10⁻³.
- Mole: quantity of substance containing the same number of entities as atoms in 12 g of carbon-12; molar mass: mass of one mole of a substance; sodium chloride molar mass is 58.44 g/mol.
- Characteristics of cathode rays include: they are negatively charged, travel in straight lines, and cause fluorescence.
- Limitations of Rutherford atomic model include lack of explanation for atomic stability and emission spectra; wave number unit: m⁻¹.
- Bohr's atomic model postulates include quantized energy levels, electron transitions result in electromagnetic emission/absorption, and energy levels correlate with principal quantum number.
- Quantum numbers (n, l, m_l) provide information on electron location, energy, and angular momentum in an atom.
Part E: Problem Solving
- Empirical and molecular formulas can be deduced through percentage composition and molar mass; utilize atomic masses for calculations.
- Molar mass of C2H5OH is 46 g/mol; percentage of C can be calculated based on mass contribution.
- Molarity formula involves moles per volume in liters; calculate using mass of solute and volume of solution for Sucrose.
- Wavelength and wavenumber calculated from the Balmer series formula for hydrogen spectrum transitions.
- De-Broglie wavelength from velocity of electron uses the formula λ = h/mv; implies wave-particle duality of matter.
- Energy of photons can be determined from frequency using Planck's equation (E = hν).
- Wavelength and wave number calculations for low-frequency broadcasts shows usage of electromagnetic radiation formulas.
Conclusion
Study these points for a solid understanding of P.U.C. First Year Chemistry, focusing on concepts, calculations, and definitions.
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Description
Test your knowledge with this midterm quiz for Chemistry PU.C. First Year. Covering essential concepts including molecular polarity and bond pair repulsion, this quiz is essential for students preparing for their exams. Challenge yourself and see how well you understand the key topics in chemistry.
