AS OCR Chemistry Unit 1

Modules 1, 2 and 3. I have tried to make it hard so that a lot of thought goes into the answers. Good Luck.


Please tell me if any of the answers are wrong it took a lot of time to make so I may have been clumsy in some places. :)

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1. What is Avogadro's constant to three significant figures?

  • 6.66 times 10 to the power of 76
  • 7.03 times 10 to the power of 11
  • 6.02 times 10 to the power of 23
  • 9.08 times 10 to the power of 32
  • 6.04 times ten to the power of 45
1 of 31

Other questions in this quiz

2. What is the definition of empirical formula?

  • The ratio of protons to neutrons
  • The simplest whole number ration of atoms of each element present in a compound
  • The actual number of atoms of each element in a molecule
  • The actual number of protons and neutrons in an element

3. At RTP what is the molar volume of any gas?

  • 300dm3
  • 24cm3
  • 24dm3
  • 21cm3
  • 21dm3

4. A compound has an empirical formula of SCl and a relative molecular mass of 135.2, find the molecular formula.

  • S2Cl2
  • S3Cl6
  • SCL4
  • S4Cl4
  • SCl

5. What is the unit that concentration is measured in?

  • mol dm3
  • mol3 conc
  • mol dm-3
  • mol conc3
  • conc




can you put the right answer plz.cause i wanna know wat i got wrong .

Sane Insanity


i have. just click the Show The Answers button after you have seen your results. If is in the place of te Submit button that was there before you submitted your answers



Half your answers are wrong. O has a higher ionisation energy than N because ionisation increases across a period!

Sane Insanity


JANDU Question 21 is correct. Ionisation does increase across a period but in some cases such as from Nitrogen to Oxygen. The first ionisation energy of Oxygen is less than that of Nitrogen as Nitrogen has a half filled subshell (Nitrogen's electron configuration being 1s2 2s2 2p3) . In oxygen the electron configuration is 1s2 2s2 2p4. However half filled subshells have more energy than subshells which contain more electrons (excluding full shells). Therefore nitrogen is more stable than oxygen as the p subshell which can hold up to 6 electrons contains half that number, so this increased stability makes it harder to remove an from nitrogen than it does to remove one from oxygen. 

Sane Insanity


Modified the ones that had typos or mistakes



Q28:"Is CCl4 polar or non-polar"

this is quite a misleading question as you are not specific in what you are asking (about the bond or the whole molecule itself)

ccl4 is a  polar molecule with polar bonds. 

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