How many d electrons are present in the Ti²⁺ ion (Ti, Z = 22)?
Correct answer B. 2
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MDCAT ECAT Chemistry MCQs
Page 7 of MDCAT ECAT Chemistry multiple-choice questions with answers. Tap an option to check yourself.
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- Gases 40
- Liquids 40
- Solids 40
- Chemical Equilibrium 40
- Reaction Kinetics 40
- Thermochemistry and Energetics 40
- Electrochemistry 40
- Fundamental Concepts of Chemistry 40
- Atomic Structure 39
- Chemical Bonding 39
- Alcohols and Phenols 38
- Industrial Chemistry 37
- Aldehydes and Ketones 37
- Alkyl Halides 37
- s- and p-Block Elements 37
- Chemistry of Hydrocarbons 36
- Fundamental Principles of Organic Chemistry 36
- Carboxylic Acids 36
- Transition Elements 35
- Macromolecules 35
A system releases 50 J of heat while 30 J of work is done on it. What is the change in its internal energy?
Correct answer C. −20 J
For N₂(g) + 3H₂(g) → 2NH₃(g) at 298 K, ΔU = −87.4 kJ. What is ΔH (R = 8.314 J K⁻¹ mol⁻¹)?
Correct answer D. −92.4 kJ
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Given ΔHc of C(s) = −393.5, H₂(g) = −285.8 and CH₄(g) = −890.3 kJ mol⁻¹, what is the standard enthalpy of formation of methane?
Correct answer D. −74.8 kJ mol⁻¹
What is the approximate enthalpy of neutralisation of a strong acid by a strong base in dilute solution?
Correct answer D. −57.3 kJ mol⁻¹
The enthalpy of atomisation of an element is the enthalpy change when ____
Correct answer B. one mole of gaseous atoms is formed from the element in its standard state
The enthalpy of solution of a substance is the enthalpy change when ____
Correct answer D. one mole of it dissolves in enough solvent to give an infinitely dilute solution
Which conditions are used for standard enthalpy changes in thermochemistry?
Correct answer A. 298 K and 1 atm (101.325 kPa)
A simple coffee-cup (glass) calorimeter open to the atmosphere directly measures which quantity?
Correct answer A. ΔH, since the reaction occurs at constant pressure
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A gas expands by 2.0 dm³ against a constant external pressure of 1.0 atm. What work is done on the gas (1 dm³ atm = 101.3 J)?
Correct answer D. −203 J
What is the oxidation number of sulphur in H₂SO₄?
Correct answer A. +6
What is the oxidation number of chlorine in potassium chlorate, KClO₃?
Correct answer A. +5
What is the oxidation number of hydrogen in sodium hydride, NaH?
Correct answer C. −1
What is the oxidation number of oxygen in hydrogen peroxide, H₂O₂?
Correct answer C. −1
What is the average oxidation number of carbon in glucose, C₆H₁₂O₆?
Correct answer A. 0
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In the reaction 2Fe³⁺ + Sn²⁺ → 2Fe²⁺ + Sn⁴⁺, which species is the reducing agent?
Correct answer C. Sn²⁺
Which reaction is an example of disproportionation?
Correct answer B. 2H₂O₂ → 2H₂O + O₂
When the equation MnO₂ + HCl → MnCl₂ + Cl₂ + H₂O is balanced, what is the coefficient of HCl?
Correct answer C. 4
In neutral or weakly basic solution MnO₄⁻ is reduced to MnO₂. What is the change in the oxidation number of manganese?
Correct answer A. Decrease by 3
During the electrolysis of molten sodium chloride, what is formed at the cathode and the anode respectively?
Correct answer D. Sodium metal and chlorine gas