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🧪 Chemistry, NCEA

Years 11 to 13 · Read up first

10 questions. Get 8 right to earn 10 minutes. All 10 right = +5 bonus. They start easy and get harder as you go, so treat the first few as a warm-up. Every one you miss comes back with the answer and why.

1. Ionic bonding occurs between

a metal and a non-metal, through transfer of electronstwo identical atoms onlytwo non-metals, through sharing electronstwo metals, through a sea of delocalised electrons

2. Alkanes are hydrocarbons that contain only

an -OH groupsingle carbon-carbon bonds (they are saturated)at least one carbon-carbon double bonda carbon-oxygen double bond

3. Elements in the periodic table are arranged in order of increasing

atomic number (number of protons)alphabetical orderatomic mass onlynumber of neutrons

4. The mole is a unit used to count

the volume of a gas onlythe number of protons in an atoma fixed number of particles (atoms, molecules or ions), equal to Avogadro's numbergrams of a substance directly

5. Concentration in mol/L (molarity) is calculated using

moles of solute multiplied by volume in litresvolume of solution divided by moles of solutemass of solute divided by mass of solventmoles of solute divided by volume of solution in litres

6. Alkenes can be distinguished from alkanes using bromine water because alkenes

explode instantly on contacthave no reaction with bromine water at allturn bromine water bluedecolourise bromine water rapidly, as the double bond reacts with it

7. Reduction is best defined (in terms of electrons) as

loss of neutronsgain of electronsloss of electronsgain of protons

8. How many moles are in 20 grams of a substance with a molar mass of 40 g/mol?

0.5220800

9. Which of these best explains why noble gases (Group 18) are generally unreactive?

They only exist as liquids at room temperatureThey have no electrons at allThey are all radioactiveThey already have a full outer electron shell, so they have little tendency to gain, lose or share electrons

10. A strong acid and a weak acid have the same concentration (same moles per litre). Which statement is correct?

pH cannot be compared between strong and weak acidsThe strong acid has a lower pH, because it ionises more fully in water, releasing more H+ ionsThe weak acid has a lower pH, because it is weakerBoth acids have exactly the same pH, since concentration is identical

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