Chemistry MDCAT MCQs
Organic, inorganic & physical chemistry MCQs
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Answer: Acidic strength of hydrohalic acids increases down the group (HCl < HBr < HI) because bond dissociation energy decreases as atomic size increases.
Answer: H3PO4 is triprotic (3 replaceable H+ ions). Normality = Molarity x n-factor = 1 x 3 = 3 N.
Answer: Electronegativity generally increases across a period because effective nuclear charge increases, attracting bonding electrons more strongly.
Answer: Water has two O-H bonds and two lone pairs on oxygen, giving it a bent molecular geometry.
Answer: At STP (0 degrees C, 1 atm), 1 mole of an ideal gas occupies 22.4 liters according to Avogadro\'s law.
Answer: Bond length increases as bond order decreases: C-C triple bond (C2H2) < C=C double bond (C2H4) < C-C single bond (C2H6).
Answer: The double bond starts at carbon 2 in the four-carbon chain, so the IUPAC name is but-2-ene.
Answer: C6H4Cl2 has three positional isomers: 1,2-dichlorobenzene (ortho), 1,3-dichlorobenzene (meta), and 1,4-dichlorobenzene (para).
Answer: AlCl3 has an incomplete octet on aluminum, allowing it to accept an electron pair, which defines a Lewis acid.
Answer: Alizarin is a mordant dye that requires a metallic mordant (like aluminum hydroxide) to bind to fabric, producing a vivid red color.
Answer: In peroxides (like H2O2 and Na2O2), oxygen has an oxidation state of -1 because the O-O bond involves shared electrons equally.
Answer: Moles of NaCl = 5.85/58.5 = 0.1 mol. Molarity = 0.1 mol / 0.5 L = 0.2 M.
Answer: Ethene (an alkene with a C=C double bond) undergoes addition reactions because the pi bond is relatively weak and can be broken to add atoms.
Answer: Cl has 7 valence electrons. Three are used for bonding with F, leaving 4 electrons = 2 lone pairs, giving a T-shaped molecular geometry.
Answer: Nylon-6,6 is formed by condensation of adipic acid and hexamethylenediamine with loss of water, making it a condensation polymer.
Answer: Molar mass of H2O = 18 g/mol. Moles = 36/18 = 2 moles.
Answer: Mg has a stable 3s2 fully filled subshell, making its first ionization energy higher than Na (3s1), Al (3s2 3p1), and Si (3s2 3p2).
Answer: CCl4 has a tetrahedral geometry with four identical C-Cl bonds. The bond dipoles cancel out, making the molecule nonpolar.
Answer: Water has sp3 hybridization with two bonding pairs and two lone pairs. The lone pair repulsion compresses the H-O-H angle from 109.5 to about 104.5 degrees.
Answer: CaO is a basic oxide formed from a metal (Ca). It reacts with water to form Ca(OH)2 and with acids to form salts.