When ammonium chloride dissolves in water, the beaker feels cold. What does this show?
Correct answer C. The dissolution is endothermic
Subject / 763 questions
MDCAT ECAT Chemistry MCQs
Page 10 of MDCAT ECAT Chemistry multiple-choice questions with answers. Tap an option to check yourself.
Page 10 of 39
- 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 beaker of hot water left open to the air can exchange both heat and water vapour with its surroundings. It is an example of ____
Correct answer C. an open system
Which pair of quantities are both path functions rather than state functions?
Correct answer D. Heat and work
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The specific heat capacity of water is 4.18 J g⁻¹ K⁻¹. What is its molar heat capacity (H₂O = 18 g mol⁻¹)?
Correct answer A. 75.2 J mol⁻¹ K⁻¹
Neutralising 0.050 mol of HCl with excess NaOH releases 2.85 kJ of heat. What is the enthalpy of neutralisation?
Correct answer D. −57 kJ mol⁻¹
How much heat is released when 4.5 g of steam condenses at 100 °C (ΔHvap = 40.7 kJ mol⁻¹, H₂O = 18 g mol⁻¹)?
Correct answer A. 10.2 kJ
In liquid and solid hydrogen fluoride, the HF molecules are linked by hydrogen bonds into ____
Correct answer B. zig-zag chains
Which hydrogen halide has the highest boiling point?
Correct answer B. HF
How does the strength of a hydrogen bond compare with that of a typical covalent bond?
Correct answer A. It is much weaker
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Hydrogen bonding occurs when a hydrogen atom is covalently bonded to ____
Correct answer B. a small, highly electronegative atom such as F, O or N
Why do water pipes sometimes burst in severe winter?
Correct answer D. Water expands when it freezes into ice
The two strands of a DNA double helix are held together by ____
Correct answer C. hydrogen bonds between complementary bases
At a given temperature, which factor makes the vapour pressure of a liquid lower?
Correct answer D. Stronger intermolecular forces
Ethanol (C₂H₅OH) boils at 78 °C while dimethyl ether (CH₃OCH₃), with the same molecular formula, boils at about −24 °C. Why?
Correct answer B. Ethanol molecules form hydrogen bonds with each other
Two different substances that have the same crystal structure are called ____
Correct answer B. isomorphic
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Polymorphism shown by an element, such as diamond and graphite for carbon, is called ____
Correct answer A. allotropy
The temperature at which two crystalline forms of a substance can exist together in equilibrium is called the ____
Correct answer D. transition temperature
How many parameters are needed to describe a unit cell completely?
Correct answer B. Six
How many Bravais lattices are possible in three dimensions?
Correct answer D. 14
An ionic crystal has a cation to anion radius ratio between 0.225 and 0.414. What arrangement is expected around each cation?
Correct answer A. Tetrahedral, coordination number 4