0% Chemistry- MDCATChemistry in MDCAT assesses essential chemical principles for medical fields. It is a core component of the standardised test for admission to Pakistani medical and dental colleges. The section evaluates understanding of organic, inorganic, and physical chemistry relevant to biological sciences. 1 / 100The order of reactivity of halogens in halogenation of alkanes is: I₂ > Br₂ > Cl₂ > F₂ Br₂ > Cl₂ > F₂ > I₂ Cl₂ > F₂ > Br₂ > I₂ F₂ > Cl₂ > Br₂ > I₂ 2 / 100The oxidation state of chromium in K₂Cr₂O₇ is: +6 +7 +4 +2 3 / 100The bond angle in a water molecule is approximately: 104.5° 180° 109.5° 120° 4 / 100The chemical formula for water is: H₂O CO₂ O₂ NaCl 5 / 100Which element shows the phenomenon of allotropy? Sodium Magnesium Carbon Calcium 6 / 100 Which hydrocarbon undergoes substitution reactions readily? Alkane Alkene Alkyne All of these 7 / 100The half-life of a first-order reaction is 10 minutes. The time required for the concentration to decrease from 0.1 M to 0.025 M is: 10 minutes 20 minutes 40 minutes 30 minutes 8 / 100Which sub-shell has the lowest energy? 5s 4s 3d 4p 9 / 100The number of isomers possible for C₄H₈ (excluding stereoisomers) is: 5 4 3 6 10 / 100Which salt solution has pH greater than 7? CH₃COONa NaCl CuSO₄ NH₄Cl 11 / 100Which of the following is a homogeneous mixture? Soil Sand and water Milk Sugar solution 12 / 100The general formula for alkanes is: CₙH₂ₙ CₙH₂ₙ₋₂ CₙH₂ₙ₊₂ CₙHₙ 13 / 100The reaction CH₃COOH + C₂H₅OH ⇌ CH₃COOC₂H₅ + H₂O is an example of: Polymerization Esterification Saponification Hydrolysis 14 / 100The standard enthalpy of formation (ΔH°f) for which of the following substances is zero? H₂O(l) CO₂(g) C(diamond) O₂(g) 15 / 100The IUPAC name of CH₃-CH₂-CH(CH₃)-CHO is: 2-Ethylpropanal Pentanal 3-Methylbutanal 2-Methylbutanal 16 / 100The osmotic pressure of a 0.1 M solution of a non-electrolyte at 27°C (R=0.0821 L.atm/mol.K) is: 24.6 atm 1.23 atm 0.246 atm 2.46 atm 17 / 100The unit of molarity is: mol/kg mol/L g/L ppm 18 / 100In the electrolysis of aqueous CuSO₄ using copper electrodes, the: Concentration remains the same Concentration of CuSO₄ decreases pH decreases Concentration of CuSO₄ increases 19 / 100The pH of a neutral solution at 25°C is: 7 9 11 3 20 / 100Which subatomic particle is located in the nucleus of an atom? Proton only Proton and Neutron Electron only Neutron only 21 / 100What is the charge on a proton? Negative Neutral Positive Variable 22 / 100The rate of a chemical reaction generally: Decreases with increase in temperature Increases with increase in temperature Is unaffected by temperature First increases then decreases 23 / 100The number of π-bonds in benzene is 9 6 12 3 24 / 100 The chemical formula of gypsum is: CaSO₄ CaSO₄·2H₂O CaCO₃ CaSO₄·½H₂O 25 / 100In the decomposition of KClO₃ to KCl and O₂, 0.1 moles of KClO₃ produces how many grams of O₂? (O=16) 1.6 g 4.8 g 3.2 g 9.6 g 26 / 100Which quantum number determines the shape of an orbital? Magnetic quantum number Principal quantum number Azimuthal quantum number Spin quantum number 27 / 100The reagent used to distinguish between aldehyde and ketone is: NaHCO₃ Fehling's solution Litmus solution Br₂ water 28 / 100The E° values for Fe³⁺/Fe²⁺ and I₂/I⁻ are +0.77 V and +0.54 V respectively. The feasibility of the reaction 2Fe³⁺ + 2I⁻ → 2Fe²⁺ + I₂ is: At equilibrium Spontaneous Non-spontaneous Cannot be predicted 29 / 100In a face-centered cubic (FCC) crystal lattice, the number of atoms per unit cell is: 1 2 6 4 30 / 100Which of the following is a noble gas? Neon Nitrogen Chlorine Oxygen 31 / 100A substance that turns blue litmus paper red is: A base An acid Neutral A salt 32 / 100 A buffer solution is prepared by mixing: Weak acid and its salt Strong base and its salt Weak base and a strong acid Strong acid and its salt 33 / 100The shape of a methane (CH₄) molecule is: Tetrahedral Bent Trigonal Planar Linear 34 / 100The hybridization of carbon in ethyne (C₂H₂) is: sp³ dsp² sp sp² 35 / 100Which element has the highest electronegativity? Fluorine Oxygen Nitrogen Chlorine 36 / 100Which complex shows optical isomerism? [Pt(NH₃)₂Cl₂] [Co(NH₃)₅Cl]²⁺ [Co(NH₃)₆]³⁺ [Co(en)₃]³⁺ 37 / 100 The symbol 'Na' represents the element: Sodium Nitrogen Nickel Neon 38 / 100In the reaction: Zn + 2HCl → ZnCl₂ + H₂, zinc acts as: Reducing agent Catalyst Oxidizing agent Electrolyte 39 / 100The atomic number of an element is defined as the number of: Protons and neutrons Electrons only Neutrons only Protons only 40 / 100A solution with a pH of 3 is how many times more acidic than a solution with a pH of 5? 1000 times 10 times 100 times 2 times 41 / 100A covalent bond is formed by the: Sharing of electrons Sharing of protons Transfer of electrons Donation of protons 42 / 100 Which alcohol gives iodoform test? Ethanol Methanol Benzyl alcohol n-Butanol 43 / 100 According to Boyle's law, at constant temperature: P ∝ T V ∝ T P ∝ 1/V V ∝ n 44 / 100The number of atoms in 4.2 g of nitrogen gas (N₂) is: 3.612 × 10²³ 1.204 × 10²⁴ 6.02 × 10²³ 1.806 × 10²³ 45 / 100The crystal structure of NaCl is: Face-centered cubic Simple cubic Hexagonal close-packed Body-centered cubic 46 / 100The compound that will undergo the Cannizzaro reaction is: Benzaldehyde Acetaldehyde Formalin Acetone 47 / 100For a reaction: 2A + B → Products, when concentration of B is doubled, the rate doubles. When concentration of A is doubled, the rate becomes four times. The rate law is: Rate = k[A][B]² Rate = k[A]²[B] Rate = k[A]²[B]² Rate = k[A][B] 48 / 100The number of isomers possible for C₄H₁₀O (alcohols) is: 2 5 3 4 49 / 100The correct order of reactivity towards nucleophilic substitution reaction for the following is: (I) CH₃-CH₂-Cl (II) (CH₃)₂CH-Cl (III) CH₃-CH₂-Br II > I > III III > I > II I > III > II I > II > III 50 / 100 The catalyst used in the Haber process for ammonia synthesis is: Iron with promoters Platinum Vanadium pentoxide Nickel 51 / 100The number of possible structural isomers for C₇H₁₆ is: 8 11 9 10 52 / 100According to the Kinetic Molecular Theory, the pressure of a gas is due to: The attraction between gas molecules The volume occupied by the gas molecules The weight of the gas molecules The collision of gas molecules with the container walls 53 / 100According to Le Chatelier's Principle, if the temperature is increased for an exothermic reaction at equilibrium, the equilibrium will shift: It will not shift To the right, favoring products First to the right, then to the left To the left, favoring reactants 54 / 100The vertical columns in the periodic table are called: Groups Blocks Periods Rows 55 / 100In a chemical reaction, the substance that is completely consumed first is called the: Excess reactant Product Catalyst Limiting reactant 56 / 100 Which of the following is a compound? Iron Oxygen Water Air 57 / 100What is the atomic number of an element with 12 protons and 12 neutrons? 18 24 12 6 58 / 100The process by which a solid changes directly into vapor without passing through the liquid state is called: Fusion Sublimation Evaporation Condensation 59 / 100 The magnetic moment of [Fe(CN)₆]⁴⁻ is: 0 BM 1.73 BM 2.83 BM 4.90 BM 60 / 100Which halogen is a liquid at room temperature? Iodine Bromine Fluorine Chlorine 61 / 100In the electrolysis of molten NaCl, the product at the cathode is: Oxygen gas Hydrogen gas Sodium metal Chlorine gas 62 / 100 In a face-centered cubic lattice, a unit cell is shared by how many unit cells? 4 8 6 2 63 / 100The half-life of a first-order reaction is 10 minutes. The time taken for the concentration of the reactant to decrease from 1.0 M to 0.125 M is: 30 minutes 40 minutes 20 minutes 10 minutes 64 / 100 The mass of one mole of electrons is approximately: 0.184 g 9.1 g 0.55 mg 1.008 g 65 / 100The process of a solid changing directly into a gas is called: Evaporation Sublimation Condensation Melting 66 / 100For a reaction, ΔG is negative. This means the reaction is: Non-spontaneous Spontaneous Fast At equilibrium 67 / 100The mass of 2.24 L of CO₂ gas at STP is: 22 g 44 g 2.2 g 4.4 g 68 / 100The oxidation state of sulfur in H₂SO₄ is: +2 +4 -2 +6 69 / 100The pH of a neutral solution at 25°C is: 0 10 14 7 70 / 100Which compound will exhibit geometrical isomerism? CH₃-CH=CH₂ CH₃-C≡C-CH₃ CH₃-CH=CH-CH₃ CH₂=CH₂ 71 / 100Which state of matter has a definite volume but no definite shape? Solid Gas Plasma Liquid 72 / 100The rate constant of a reaction is 2.3 × 10⁻⁵ L mol⁻¹ s⁻¹. The order of reaction is: 3 4 5 2 73 / 100 The order of stability of the following carbocations is: (I) (CH₃)₃C⁺ (II) CH₃-CH₂⁺ (III) (CH₃)₂CH⁺ II > III > I I > II > III III > II > I I > III > II 74 / 100The catalyst used in the Contact Process for sulfuric acid manufacture is: Nickel Platinum Iron Vanadium pentoxide 75 / 100A compound contains 40% carbon, 6.7% hydrogen, and 53.3% oxygen. Its empirical formula is: C₆H₁₂O₆ C₃H₆O₃ C₂H₄O₂ CH₂O 76 / 100The boiling point of water at 700 mmHg pressure is: 0°C Less than 100°C More than 100°C 100°C 77 / 100Which halogen exists as a liquid at room temperature? Iodine Fluorine Chlorine Bromine 78 / 100The process used to convert vegetable oils into fats is: Saponification Halogenation Hydrogenation Oxidation 79 / 100The compound that gives a positive Tollens' test but negative Fehling's test is: Acetaldehyde Formaldehyde Benzaldehyde Acetone 80 / 100The complex ion [CoF₆]³⁻ is paramagnetic. The hybridization of cobalt in this complex is: sp³ sp³d² dsp² d²sp³ 81 / 100The number of moles in 44 grams of CO₂ (C=12, O=16) is: 0.5 3 1 2 82 / 100The shape of a water molecule is: Bent Tetrahedral Trigonal planar Linear 83 / 100Which of the following is an example of a covalent network solid? Copper Diamond Ice Sodium chloride 84 / 100The pH of 0.01 M CH₃COOH solution (Ka = 1.8 × 10⁻⁵) is approximately: 5.8 4.7 2.0 3.4 85 / 100The crystal field splitting energy (Δo) for an octahedral complex is: Independent of the charge on the central metal ion Directly proportional to the charge on the central metal ion Inversely proportional to the charge on the central metal ion Zero for transition metal complexes 86 / 100The process used for the purification of copper is: Calcination Electrolytic refining Roasting Smelting 87 / 100The Haber process is used for the industrial production of: Nitric Acid Urea Sulfuric Acid Ammonia 88 / 100In the electrochemical series, the standard electrode potential is measured relative to: Silver-silver chloride electrode Standard hydrogen electrode Zinc electrode Calomel electrode 89 / 100The E° value for the standard hydrogen electrode is assigned a value of: 1.00 V 0.00 V -1.00 V 2.00 V 90 / 100The IUPAC name for CH₃-CH₂-CHO is: Propanone Propanal Butanal Ethanal 91 / 100The SI unit of pressure is: Atmosphere Torr Pascal Bar 92 / 100How many electrons can the first shell (K-shell) of an atom hold? 0 1 3 2 93 / 100Which of the following has the highest boiling point? H₂O HCl NH₃ CH₄ 94 / 100 The density of a gas is 2.0 g/L at 1 atm pressure and 27°C. Its molecular mass is: 44.8 22.4 64.5 49.2 95 / 100The rate law for a reaction is found to be Rate = k [A]²[B]. If the concentration of A is doubled and B is halved, the rate of reaction will: Become half Become four times Remain the same Become double 96 / 100The percentage of s-character in the hybrid orbitals of ethane, ethene, and ethyne follows the order: Ethene > Ethane > Ethyne Ethyne > Ethane > Ethene Ethane > Ethene > Ethyne Ethyne > Ethene > Ethane 97 / 100Which of the following is a strong electrolyte? Acetic acid Ethanol Sugar solution Sodium chloride solution 98 / 100 The number of σ and π bonds in CH₂=CH-C≡N are: 7σ, 2π 5σ, 3π 6σ, 3π 8σ, 1π 99 / 100Which quantum number defines the shape of an orbital? Spin quantum number (s) Azimuthal quantum number (l) Principal quantum number (n) Magnetic quantum number (m) 100 / 100Which of the following has the highest boiling point? C₄H₁₀ CH₄ C₃H₈ C₂H₆ Your score isThe average score is 68% 0% Restart quiz