20 chemistry questions

Common Entrance Chemistry – 20 Multiple choice questions
Answer all 20 questions and then press ‘Submit’
Your score and any corrections will then be shown
(Different questions each time the quiz is run)

1. air

Look at the diagram above.

100 cm3 of air is put in one of the syringes. When the copper is heated it reacts with the oxygen in the air inside the syringe.

The syringe plungers are moved in and out so that all of the air is passed over the hot copper. When there is no further change the apparatus is allowed to cool (to allow the heated air to contract.Some copper remains unreacted because there is no oxygen left in the syringe.The gas remaining in the syringe is mostly nitrogen.ResultsVolume of air in syringe at start = 100cm3
Volume of air in syringe after heating = 79 cm3
 What volume of air was used up by the copper?

2. What colour would Universal Indcator turn when added to a mild alkali?

3. What is the approximate number of elements?

4. Name a chemical that decomposes to release carbon dioxide when it is heated

5. Word equations for 4 different reactions are shown.
Which of them shows oxidation and reduction taking place?

6. What will chocolate do when heated gently in an open dish

7. C is the symbol for which chemical element

8. If a cup of tea is to kept warm it needs to be wrapped in what kind of material?

9. When copper foil is heated with a roaring bunsen flame and it quickly turns black.
What is the name of the black chemical formed?

10. Which of the below is not an example of a chemical change?

11. About 20cm of magnesium ribbon is chopped up into 1cm lengths and placed in a crucible which is then weighed along with its lid.

The crucible is heated strongly and the lid gently raised avery few seconds.
When the lid was raised a bright glow was seen to spread through the mixture

When the reaction is over the crucible + contents + lid are all re-weighed.
A white ash remains in the crucible.

These are his results:
  • Mass of empty crucible + lid  = 51.2g
  • Mass of crucible + lid + magnesium (before heating) = 54.3g
  • Mass of crucible + lid + contents (after heating) = 54.7g
 

What evidence is there that a chemical change is taking place?
(read all options before answering) 

12. This diagram shows the water cyclewater cycle3 Where does the energy come from that drives the water cycle?
 

 

13. What percentage of the air is oxygen (approximately)?

14. From the list below pick the best conductor of heat

15. Which of the below is a fossil fuel?

16. What colour would Universal Indcator turn when added to a strong acid?

17. apparatus3What is the purpose of the piece of apparatus shown?

18. The substance found in pencil 'leads' is made from

19. Cu is the symbol for which chemical element

20. A liquid with a pH of 6 would be described as .....