The wave number of a radiation is defined as ____
Correct answer B. the number of waves per unit length, equal to 1/λ
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MDCAT ECAT Chemistry MCQs
Page 14 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
What values can the azimuthal quantum number l have when n = 3?
Correct answer A. 0, 1, 2
How many values of the magnetic quantum number m are possible when l = 2?
Correct answer C. 5
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What is the maximum number of electrons that can have the quantum numbers n = 3 and l = 1?
Correct answer C. 6
Indigo is applied to cotton as a vat dye. Which statement describes this process?
Correct answer A. It is reduced to a soluble leuco form, absorbed by the fibre, then oxidised back in air
What is the role of a mordant, such as alum, in dyeing?
Correct answer A. It binds the dye to the fibre by forming an insoluble complex
Which type of dye is most suitable for polyester fibres?
Correct answer B. Disperse dyes
Which dyes can be applied to cotton from an aqueous bath without a mordant?
Correct answer A. Direct dyes
Acid dyes are used mainly for which group of fibres?
Correct answer C. Wool, silk and nylon
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Why do reactive dyes show excellent wash fastness on cotton?
Correct answer C. They form covalent bonds with the hydroxyl groups of cellulose
Which monomer can undergo addition polymerisation?
Correct answer B. Chloroethene, CH₂=CHCl
Nylon-6,6 is made from hexane-1,6-diamine and hexanedioic acid. Which small molecule is eliminated as each amide link forms?
Correct answer A. Water
Terylene (PET) is a polyester made from which pair of monomers?
Correct answer A. Ethane-1,2-diol and benzene-1,4-dicarboxylic acid
Bakelite, made from phenol and methanal, is used for electrical switches. Which property explains why it does not soften on heating?
Correct answer B. It is a thermosetting polymer with extensive cross-linking
Why can a thermoplastic such as polyethene be melted and remoulded many times?
Correct answer B. Its chains are held by weak intermolecular forces with no cross-links
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Take ethene, C₂H₄ = 28 g/mol. A sample of polyethene has an average molar mass of 42 000 g/mol. What is its average degree of polymerisation?
Correct answer A. 1500
Take C = 12, H = 1, Cl = 35.5. What is the percentage by mass of chlorine in PVC, whose repeat unit is –CH₂–CHCl–?
Correct answer D. 56.8%
A sample of nylon-6,6 has an average molar mass of 45 200 g/mol. The repeat unit, C₁₂H₂₂N₂O₂, has a molar mass of 226 g/mol. How many repeat units are in an average chain?
Correct answer C. 200
In a plant, 2.1 tonnes of propene is fed into a reactor and 90% of it is converted into polypropene. What mass of polypropene is produced?
Correct answer B. 1.89 tonnes
Take C = 12, F = 19. What is the percentage by mass of fluorine in PTFE (Teflon), whose repeat unit is –CF₂–CF₂–?
Correct answer C. 76.0%