Is Matter Around Us Pure? quiz

Which of these is a homogeneous mixture?

The scattering of a beam of light by colloidal particles is called:

Which method is used to separate cream from milk?

Which of these is a compound?

Milk is an example of a:

Different dyes in black ink can be separated by:

Which of these is a metalloid?

A suspension is:

Which is a chemical change?

Two miscible liquids whose boiling points differ by less than 25 K are separated by:

Why is a solution of sugar in water called a homogeneous mixture? (2 marks)

What is an alloy? Why is it considered a mixture? (2 marks)

How does solubility of a solid in water change with temperature? (2 marks)

Name the dispersed phase and dispersion medium in fog, smoke and shaving cream. (2 marks)

Why does a beam of sunlight become visible in a dense forest? (2 marks)

Give two applications of centrifugation. (2 marks)

Why is crystallisation used to purify copper sulphate? (2 marks)

Name two substances that sublime. (2 marks)

Give two differences between a mixture and a compound. (2 marks)

Name two uses of chromatography. (2 marks)

A solution has 25 g of sugar dissolved in 225 g of water. Find the mass by mass percentage. (3 marks)

How much salt and water are needed to prepare 500 g of a 5% salt solution by mass? (3 marks)

A solution has 12 g of urea in 300 mL of solution. Find its mass by volume percentage. (3 marks)

The solubility of potassium nitrate is 32 g per 100 g of water at 293 K. How much potassium nitrate is needed to make a saturated solution in 50 g of water at this temperature? (3 marks)

A 20% by mass solution of glucose has a mass of 150 g. Find the mass of glucose. If 50 g of water is added, find the new percentage. (3 marks)

Read the passage and answer the questions. A teacher shines a torch beam through three beakers containing salt solution, milk and a mixture of chalk in water. The path of light is visible in two of them. (i) In which beakers is the path visible? (ii) What is this effect called? (iii) Which mixture will settle on standing? (5 marks)

Read the passage and answer the questions. In a lab, a student heats a mixture of iron filings and sulphur. The mixture glows and forms a black solid that is not attracted by a magnet. (i) What is the black solid? (ii) Is this a physical or a chemical change? Why? (iii) How would the mixture have behaved with a magnet before heating? (5 marks)

Read the passage and answer the questions. In a refinery, petroleum is heated and its components, such as petrol, kerosene and diesel, are collected at different heights of a tall column. (i) Name the process used. (ii) On what property is it based? (iii) Give one more application of this process. (5 marks)

Read the passage and answer the questions. Salt is obtained from sea water in salt pans on the coasts of Gujarat. Sea water is let into shallow pans and left in the sun. (i) What method of separation is used? (ii) Why is the salt obtained this way impure? (iii) How can it be purified? (5 marks)

Read the passage and answer the questions. A doctor tells a patient that some medicines must be shaken well before use, while others need not be shaken. (i) What type of mixture needs shaking? (ii) Why do its particles settle? (iii) Name one medicine that is a true solution. (5 marks)

Draw a labelled diagram of the separation of dyes in black ink using paper chromatography. Explain the principle and two applications. (6 marks)

Draw a labelled diagram of fractional distillation. Explain how it separates two miscible liquids and how it differs from simple distillation. (6 marks)

Draw a flowchart classifying matter into pure substances and mixtures with all sub-types and examples. (6 marks)

Draw a labelled diagram of the crystallisation of copper sulphate. Explain the steps and why it is preferred over evaporation. (6 marks)

Draw a flowchart of the steps followed in a water purification plant in a city. Explain the separation method used at each step. (6 marks)