Chemistry Section 4

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• The quantum number indicating electron energy is ‘n’.
• Neutrons can expel protons from paraffins.
• Attractive forces balance centrifugal forces in atoms.
• When the 6d orbital is complete, the next electron enters the 7p orbital.
• Neutrons moving with 1.2 MeV energy are considered fast neutrons.
• Chromatography classification is based on shape, phase, and mechanism.
• Filtration separates insoluble particles from liquids.
• Fluted filter paper increases filtration rate.
• A substance with high vapor pressure at its melting point undergoes sublimation.
• Ascending chromatography involves the solvent pool at the container’s bottom.
• Analytical chemistry involves qualitative and quantitative substance analysis.
• Quantitative analysis estimates amounts of components in a sample.
• Residue remains on the filter paper after filtration.
• Gooch crucibles are made of porcelain.
• Sintered crucibles are made of glass.
• Crystallization is the process of separating solids from hot saturated solutions by cooling.
• Solvent extraction is a simple and efficient method for purifying substances.
• 95% ethanol is called rectified spirit.
• Distribution coefficient measures the ratio of solute in organic and aqueous solvents.
• Animal charcoal adsorbs colored impurities.
• Crystallization doesn’t involve sublimation.
• In CCl4, I2 shows a purple color.
• Sublimation is the direct conversion of solids into vapors.
• Filtration without a suction pump is a slow process.
• CaCl2 and PCl5 are used as drying agents in crystallization.
• Solvent extraction uses ether to separate organic synthesis products from water.
• In crystallization, if the solvent is flammable, direct heating is avoided.
• Filter paper increases filtration rate when gentle suction is applied.
• Filter paper size is selected based on the amount of insoluble solute.
• Touching the funnel to the breaker wall prevents splashing during filtration.
• Sublimation is a technique to separate components of a mixture in the solid phase.
• Qualitative analysis identifies the components of a sample.
• Different components of a mixture have different Rf values due to their distribution in the solvent.
• Solvent extraction is controlled by the distributive law.
• The most reliable method of drying crystals is using a vacuum desiccator.
• Silica gel and alumina are used as stationary phases in chromatography.
• The solvent or solvent mixture used for compound separation is the mobile phase.
• Sintered glass is used for filtration.
• “Sublimate sublimation” is not a related pair of terms in analytical techniques.
• Complete quantitative analysis involves four major steps.
• Filter paper selection depends on the size of particles to be filtered.
• Potash alum does not sublime.
• Shaking two immiscible liquids increases the area of contact.
• Ionization energy generally increases from left to right in a period.
• Pi bonds are formed by the overlap of p orbitals.
• The octet rule doesn’t hold for phosphorus (P).
• CO2 is a non-polar molecule due to its dipole moment being zero.
• Electro negativity is not an absolute term of an element.
• When N2 molecule is formed, each nitrogen atom is sp2 hybridized.
• Dipole moment is the measurement of the degree of polarity.
• NH-2 has the maximum number of unpaired electrons among the options.
• The force responsible for holding atoms together in a compound is a bond.
• Atomic radius decreases across a period.
• Ionization potential is the energy required to remove an electron from an atom.
• Greater shielding effect corresponds to a lesser ionization energy.
• Electron affinity is the energy released or absorbed when electrons are added to an atom.
• Elements of group IA and IIA are electropositive.
• Ionic compounds are formed between elements of groups IA, IIA, and VIIA.
• Lewis acids are electron-deficient.
• Ammonia (NH3) has a trigonal pyramidal geometry.
• By combining n atomic orbitals, n hybrid orbitals are formed.
• The geometry of a molecule with sp3 hybridization is tetrahedral.
• Pi bonds are formed by the overlap of unhybridized orbitals.
• Antibonding molecular orbitals have higher energy than atomic orbitals.
• The bond order of N2 molecule is 3.
• Dipole moment is the product of charge and distance.
• Electronegativity represents the relative attraction of the nucleus for electrons in a chemical bond.
• Chlorine (Cl) has the highest electron affinity.
• Gases deviate from ideal behavior at low temperature and high pressure.
• Critical temperature depends on the size, shape, and intermolecular attractions of a gas.
• Element 7Y has the highest number of unpaired electrons.
• Molecular orbitals are filled according to Aufbau’s principle, Hund’s rule, and Pauli’s exclusion principle.
• Hydrogen fluoride (HF) has the highest percentage of ionic character.
• Noble gases have their outermost shells complete in atomic form.
• An atom loses or gains electrons to gain stability, form bonds, or complete its outermost shell.
• In a period, ionic radius increases.
• Electronegativity increases from left to right in a period.
• Elements with high ionization potential are nonmetals.
• Electropositive elements are metals.
• Electronegativity increases across a period.
• Ionic bonds result from the complete transfer of electrons.
• Ionic bonding occurs when the electronegativity difference of bonded atoms is greater than 1.7.
• HF has a polar covalent bond.
• Sharing one electron pair by one species forms a coordinate covalent bond.
• Degenerate orbitals have the same energy and result from the mixing of orbitals of different energy.
• The geometry of a molecule is pyramidal if the central atom has 3 bond pairs and 1 lone pair.
• A molecule with 5 bond pairs has a trigonal bipyramidal geometry according to the VSEPR model.
• Unpaired electrons in a molecule make it paramagnetic.
• Dipole moment is the product of charge and distance.
• An atom undergoes sp3 hybridization when one s and three p orbitals are involved.
• CO diffuses 1.25 times faster than CO2.
• Coordinate covalent bonds are not considered intermolecular forces between molecules.
• Ideal gases have no intermolecular forces, perfectly elastic collisions, and occupy no space.
• Gases deviate from ideal behavior at low temperature and high pressure.
• Ammonia (NH3) has the lowest density at room temperature.
• The introduction of the Kelvin scale in thermodynamics is based on Charles’s law.
• When the pressure of an ideal gas is doubled at a constant temperature, its density becomes double.
• Boyle’s law relates the volume and pressure of a gas at constant temperature.
• Charle’s law gives the relationship between volume and temperature of a gas.
• The first law of thermodynamics is a version of the law of conservation of energy.