Chemical Analysis questions

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Chemical Analysis question collection

Review Chemical Analysis questions for Chemistry, with correct answers shown and coverage across pure substances and formulations; chromatography; gas tests.

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Question 1

What does a melting range usually suggest about a sample?
  1. It contains more than one substance
  2. It is a pure compound
  3. It is a pure element
  4. It has a low boiling point

Question 2

What is a formulation?
  1. A measured mixture designed for a purpose
  2. A mixture with uncontrolled proportions
  3. A pure compound with a fixed formula
  4. A product formed accidentally in a reaction

Question 3

Which ratio gives the chromatography Rf value?
  1. Substance distance ÷ solvent-front distance
  2. Solvent-front distance ÷ substance distance
  3. Baseline distance ÷ paper length
  4. Substance distance × solvent-front distance

Question 4

If a dye spot moves \(3.0\,\mathrm{cm}\) and the solvent front moves \(6.0\,\mathrm{cm}\), what is Rf?
  1. \(0.50\)
  2. \(2.0\)
  3. \(3.0\)
  4. \(0.20\)

Question 5

What is the test for hydrogen gas?
  1. A lit splint gives a squeaky pop
  2. A glowing splint relights
  3. Limewater turns milky
  4. Damp blue litmus turns red then bleaches

Question 6

What is the test for oxygen gas?
  1. A glowing splint relights
  2. A lit splint gives a squeaky pop
  3. Limewater turns cloudy
  4. Bromine water decolourises

Question 7

What is the test for carbon dioxide gas?
  1. Limewater turns milky
  2. A glowing splint relights
  3. A lit splint gives a squeaky pop
  4. Damp red litmus turns blue

Question 8

Chlorine gas bleaches damp litmus paper. What colour change is first seen on blue litmus?
  1. Blue to red, then bleached white
  2. Blue to green
  3. Blue to purple
  4. No change on damp litmus

Question 9

Which flame test colour indicates sodium ions, \(\mathrm{Na^+}\)?
  1. Yellow
  2. Lilac
  3. Green
  4. Brick red

Question 10

Which flame colour is characteristic of potassium ions, \(\mathrm{K^+}\)?
  1. Lilac
  2. Yellow
  3. Blue-green
  4. Orange-red

Question 11

Adding sodium hydroxide to Cu2+ solution produces what observation?
  1. A blue precipitate
  2. A green precipitate
  3. A white precipitate
  4. No precipitate

Question 12

What observation is seen when sodium hydroxide is added to Fe2+ solution?
  1. A green precipitate
  2. A blue precipitate
  3. A white precipitate
  4. A yellow solution

Question 13

What observation is seen when sodium hydroxide is added to Fe3+ solution?
  1. A brown precipitate
  2. A green precipitate
  3. A blue precipitate
  4. A colourless solution

Question 14

Which test identifies carbonate ions?
  1. Add dilute acid and bubble the gas through limewater
  2. Add acidified barium chloride and look for a white precipitate
  3. Add acidified silver nitrate and look for a white precipitate
  4. Add sodium hydroxide and look for a blue precipitate

Question 15

Compared with simple chemical tests, instrumental methods are often:
  1. More sensitive and faster
  2. Less sensitive but faster
  3. More sensitive but slower
  4. Limited to pure substances

Question 16

Which white hydroxide precipitate dissolves in excess sodium hydroxide?
  1. Aluminium hydroxide
  2. Calcium hydroxide
  3. Magnesium hydroxide
  4. Copper(II) hydroxide

Question 17

What flame colour indicates lithium ions?
  1. Crimson
  2. Yellow
  3. Lilac
  4. Green

Question 18

What flame colour indicates calcium ions?
  1. Orange-red
  2. Crimson
  3. Yellow
  4. Lilac

Question 19

Which test identifies sulfate ions?
  1. Acidified barium chloride gives a white precipitate
  2. Acidified silver nitrate gives a white precipitate
  3. Dilute acid releases gas that clouds limewater
  4. Sodium hydroxide gives a blue precipitate

Question 20

Which test identifies chloride ions?
  1. Acidified silver nitrate gives a white precipitate
  2. Acidified barium chloride gives a white precipitate
  3. Dilute acid releases gas that clouds limewater
  4. Sodium hydroxide gives a green precipitate

Question 21

Which method can identify metal ions at very low concentrations?
  1. Flame emission spectroscopy
  2. Paper chromatography
  3. Acid-base titration
  4. Simple distillation

Question 22

What is a precipitate?
  1. An insoluble solid formed in a reaction
  2. A gas released during a reaction
  3. A soluble product remaining in solution
  4. A substance that speeds up a reaction

Question 23

What can a calibration curve determine?
  1. An unknown concentration from instrument response
  2. A sample's purity by filtration
  3. A gas identity from its smell
  4. A chromatography solvent from colour

Question 24

Which result shows that ammonia gas is present?
  1. Damp red litmus turns blue
  2. Damp blue litmus turns red
  3. A lit splint gives a squeaky pop
  4. A glowing splint relights

Question 25

Why must a chemical test for an ion be unique?
  1. Only one ion gives that result
  2. It makes the test faster
  3. It needs no equipment
  4. It uses up less sample

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Review Chemical Analysis questions for Chemistry, with correct answers shown and coverage across pure substances and formulations; chromatography; gas tests.

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