Physical changes and chemical reactions

9.A student observes bubbles forming when a solid is added to a liquid. Which conclusion is most likely correct?

10.Which statement about physical changes is correct?

11.A 100 g sample of ice melts to form water. The water is then boiled to steam. What is the mass of the steam?

12.Which of the following is an example of a chemical reaction?

13.A student adds a colourless liquid to a white solid. A gas is produced, and the mixture becomes hot. Which of the following is true?

14.When 100 g of ice melts, what is the mass of the water formed?

15.A student adds a colourless liquid to a white solid. The mixture becomes hot and a gas is produced. Which of the following is true?

16.A student measures the mass of a sealed flask containing 10 g of iron and 5 g of oxygen. After the iron rusts completely, the flask is weighed again. What is the total mass inside the flask?

17.A student places 50 g of ice in a beaker and leaves it on a bench. After one hour, the beaker contains 50 g of water. Which statement explains this observation?

18.A student dissolves 10 g of sugar in 100 g of water. The solution is then heated until all the water evaporates. What mass of sugar remains?

19.A student places a 100 g sample of ice in a beaker and melts it completely. The water is then boiled until it all becomes steam. What is the mass of the steam?

20.A student adds hydrochloric acid to a sample of marble chips (calcium carbonate). The mixture fizzes and a gas is produced. Which of the following is the best evidence that a chemical reaction has occurred?

21.A student heats 50 g of hydrated copper(II) sulfate (blue crystals) in a test tube. The crystals turn white and water vapour condenses on the cooler part of the test tube. After cooling, the white solid is reweighed. Which mass is most likely?

22.A student places 10 g of iron filings in a sealed flask with 5 g of oxygen. The iron rusts completely. Which statement about the mass of the flask and its contents after the reaction is correct?

23.Which of the following is a sign of a chemical reaction?

24.A teacher demonstrates the reaction between iron and sulfur. A mixture of iron filings and sulfur powder is heated strongly. A black solid forms. The black solid does not stick to a magnet, but the original iron filings did. Which conclusion is correct?

25.A student dissolves 20 g of salt in 100 g of water. The solution is then heated until all the water evaporates. What mass of salt remains?

26.A student measures the mass of a piece of magnesium ribbon before burning it in air. The ash (magnesium oxide) is collected and weighed. Which mass is expected?

27.A student adds a colourless solution of hydrogen peroxide to a black powder (manganese dioxide). Bubbles of gas are produced and the test tube feels warm. Which statement is correct?

28.A student carries out an experiment to show conservation of mass. They place 25 g of sodium hydrogencarbonate in a flask and add 50 g of dilute ethanoic acid. The flask is connected to a gas syringe. After the reaction, the flask contains a colourless solution and the gas syringe contains 12 g of carbon dioxide. What mass of solution is in the flask?

29.A student wants to separate a mixture of sand and salt. Which sequence of steps is correct?

30.A student dissolves 15 g of salt in 85 g of water. The solution is then heated until all the water evaporates. What mass of salt remains?

31.A student measures the mass of a sealed flask containing 10 g of iron wool and 5 g of oxygen. The iron rusts completely. Which statement about the mass of the flask and its contents after the reaction is correct?

32.A 50 g sample of ice is left in a beaker at room temperature. After melting, the water is boiled until it all becomes steam. What is the mass of the steam?

33.A student adds 25 cm³ of hydrochloric acid to 25 cm³ of sodium hydroxide solution. The mixture is stirred and the temperature rises from 20°C to 32°C. A colourless solution remains. Which statement is correct?

34.A 100 g sample of copper(II) sulfate crystals (blue) is heated strongly. The crystals turn white and 36 g of water vapour is given off. What is the mass of the white solid remaining?

35.A student dissolves 20 g of sugar in 100 g of water. The solution is then heated until all the water evaporates. What mass of sugar remains?

36.A student places 10 g of iron filings and 5 g of sulfur powder in a test tube and heats the mixture. A black solid forms. The test tube is weighed before and after the reaction. Which mass is expected?

37.A student heats a blue solution of copper(II) sulfate until all the water evaporates, leaving white copper(II) sulfate powder. This change is reversed by adding water to the white powder. Which statement is correct?

38.A student adds a colourless solution of hydrogen peroxide to a black powder (manganese dioxide). Bubbles of gas are produced and the test tube feels warm. Which of the following is the most likely conclusion?

39.A student heats a blue solution of copper(II) sulfate until all the water evaporates, leaving white copper(II) sulfate powder. This change is reversed by adding water to the white powder. Which statement about this process is correct?

40.A student places 10 g of iron filings and 5 g of sulfur powder in a test tube and heats the mixture. A black solid forms. The test tube is weighed before and after heating. Which mass is expected after heating?

41.A chemical reaction is easily reversible.

42.When a mass of 200 g of water evaporates, the mass of the water vapour is less than 200 g.

43.A change in colour is a sign of a physical change.

44.Gas being given out is a sign of a chemical reaction.

45.Condensation is a physical change.

46.Match each description to the correct type of change.

47.Arrange the following steps in the correct order to show how to reverse the dissolving of salt in water.

48.Which of the following are signs of a chemical reaction? (Select all that apply)

49.A student heats 10 g of hydrated copper(II) sulfate (blue crystals) in a test tube. The crystals turn white and water vapour escapes. Which statement is correct?

50.A student dissolves 10 g of salt in 100 g of water. The solution is then heated until all the water evaporates. Which mass of salt will remain?

51.Describe what is meant by the conservation of mass.

52.State two reasons why we know that the reaction between copper and oxygen is a chemical reaction.

53.Aside from colour change and temperature change, state three other signs that could show a chemical reaction has taken place.

54.A substance is changing from being a gas to being a liquid. State the name of the state change.

55.Explain why condensation is a physical change and not a chemical reaction.

56.Some table salt is dissolved in some water. Describe how we could reverse this physical change to have table salt again.

57.Complete the sentence about state changes.

58.A student reacts 7 g of iron with 4 g of sulfur to form iron sulfide. What is the mass of iron sulfide formed?

59.A student reacts 7 g of iron with 4 g of sulfur to form iron sulfide. What is the mass of iron sulfide formed?