NCERT Class 9 Science — Chapter 2: Is matter around us pure?

When a beam of light is passed through a true solution, such as copper sulphate in water:

With reference to a 'Suspension', consider the following statements: 1. It is a homogeneous mixture. 2. The solute particles remain suspended throughout the bulk of the medium. 3. The particles are too small to be seen with the naked eye. Which of the statements given above is/are correct?

The interconversion of water and water vapour is considered a physical change primarily because:

Which one of the following elements is classified as a metalloid?

The 'concentration' of a solution is quantitatively defined as:

With reference to changes in matter involving paper, consider the following statements: 1. Burning of paper is a chemical change. 2. Tearing of paper is a chemical change. 3. Folding of paper is a reversible change. Which of the statements given above is/are correct?

In a colloidal solution, the component in which the dispersed phase is suspended is technically termed as:

Which one of the following is classified as a 'Foam' or 'Solid Foam' colloid?

The 'Tyndall effect' refers to which one of the following phenomena?

Which one of the following is NOT a characteristic property of a colloidal solution?

With reference to the 'Tyndall effect', consider the following statements: 1. It is observed only in a vacuum. 2. It is due to the scattering of light by particles. 3. It is observed in colloidal solutions. Which of the statements given above is/are correct?

With reference to 'Colloidal Solutions', consider the following statements: 1. They appear homogeneous but are actually heterogeneous. 2. Their particles are large enough to be seen with the naked eye. 3. They scatter a beam of visible light. Which of the statements given above is/are correct?

In the context of solution chemistry, the terms 'dilute' and 'concentrated' are:

According to the Law of Constant Proportions, the composition of a chemical compound:

When dilute sulphuric acid is added to a physical mixture of iron filings and sulphur powder, which gas is evolved?

Consider the following statements regarding the gas evolved when dilute hydrochloric acid reacts with Iron Sulphide: 1. It is colourless. 2. It is odourless. 3. It has a pleasant smell. Which of the statements given above is/are correct?

Which one of the following characteristics distinguishes a suspension from a true solution?

The visibility of a light beam entering a dark room through a small opening is due to:

With reference to physical changes, consider the following statements: 1. Interconversion of states of matter is a physical change. 2. Physical changes involve a change in the chemical composition of the substance. 3. Physical changes always result in the formation of new substances. Which of the statements given above is/are correct?

Consider the following statements regarding the burning of wood: 1. It involves the conversion of wood into new substances like ash and smoke. 2. It is a physical change. 3. It is an irreversible process. Which of the statements given above is/are correct?

With reference to 'Compounds', consider the following statements: 1. A compound is a substance composed of two or more elements mixed in any proportion. 2. The properties of a compound are distinct from those of its constituent elements. 3. The constituents of a compound can be separated only by chemical or electrochemical reactions. Which of the statements given above is/are correct?

Consider the following statements regarding the reaction of Hydrogen gas: 1. It is combustible. 2. It burns silently without any sound. 3. It has a distinct pungent odour. Which of the statements given above is/are correct?

Consider the following statements about air: 1. It is a homogeneous mixture of gases. 2. Its two main constituents are carbon dioxide and argon. 3. It is considered a solution of gas in gas. Which of the statements given above is/are correct?

Water is chemically classified as a compound rather than a mixture because:

In the classification of colloids, 'Cheese' and 'Butter' are examples of:

Consider the following statements about elements: 1. The majority of elements are solids. 2. Only two elements are in the gaseous state at room temperature. 3. Gallium and Cesium remain solid even at temperatures well above 303 K. Which of the statements given above is/are correct?

With reference to 'Alloys', consider the following statements: 1. They are considered mixtures because they show the properties of their constituents. 2. They can be separated into their components by physical methods. 3. They have a fixed composition and cannot vary. Which of the statements given above is/are correct?

Which one of the following properties is NOT observed in a true solution?

Consider the following statements regarding homogeneous mixtures: 1. They have a non-uniform composition with visible boundaries. 2. Salt dissolved in water is an example of a homogeneous mixture. 3. A homogeneous mixture can have a variable composition. Which of the statements given above is/are correct?

From a chemical classification perspective, 'Brass' is considered a:

Consider the following statements about the properties of solutions: 1. Particles of a solution are large enough to be seen with the naked eye. 2. A solution is stable, and solute particles do not settle down. 3. The path of light is not visible in a solution. Which of the statements given above is/are correct?

Which separation technique is most appropriate for separating colloidal particles, such as cream from milk?

Which one of the following is an example of an 'Aerosol' type of colloid?

Consider the following statements distinguishing water and cooking oil: 1. They differ in odour and inflammability. 2. Water extinguishes fire, whereas oil does not burn in air. 3. They are chemically the same but physically different. Which of the statements given above is/are correct?

Consider the following statements regarding the Tyndall effect in a dense forest: 1. It is caused by the absorption of light by mist droplets. 2. Mist droplets act as colloidal particles dispersed in air. 3. This phenomenon is observed because air is a heterogeneous mixture containing dust or smoke. Which of the statements given above is/are correct?

Consider the following statements regarding the properties of metals: 1. They are generally brittle and non-ductile. 2. They are generally good conductors of heat and electricity. 3. They are sonorous. Which of the statements given above is/are correct?

With reference to the classification of elements, consider the following statements: 1. Mercury is the only metal that is liquid at room temperature. 2. Non-metals are generally lustrous and malleable. 3. Metalloids show properties intermediate between metals and non-metals. Which of the statements given above is/are correct?

Match List I with List II and select the correct answer using the code given below: List I | List II A. Mercury | 1. Liquid Non-metal B. Oxygen | 2. Gas C. Bromine | 3. Liquid Metal D. Carbon | 4. Solid

Consider the following statements regarding the scattering of light: 1. A solution of copper sulphate shows the Tyndall effect. 2. A mixture of water and milk shows the Tyndall effect. 3. Scattering makes the path of light visible. Which of the statements given above is/are correct?

Consider the following statements about 'Solubility': 1. It is the amount of solute present in a saturated solution at a given temperature. 2. Different substances have the same solubility in a given solvent at the same temperature. 3. Solubility of a substance remains constant regardless of temperature changes. Which of the statements given above is/are correct?

Consider the reaction between Iron filings and Sulphur powder. Which of the following statements is/are correct? 1. Heating the mixture strongly creates a compound that is not magnetic. 2. The gas evolved when reacting the heated compound with acid smells like burning sulphur. Select the correct answer using the code given below:

Consider the following statements about 'Metalloids': 1. They are mixtures of metals and non-metals. 2. Boron and Silicon are examples of metalloids. 3. They show properties intermediate between metals and non-metals. Which of the statements given above is/are correct?

Which one of the following is an example of a 'Solid Sol' colloid?

Which one of the following is classified as a pure substance?

Which one of the following correctly describes the dispersed phase and dispersing medium in a 'Gel'?

In colloidal chemistry, a 'Sol' is defined as:

Consider the following statements regarding the separation of mixtures: 1. Sodium chloride cannot be separated from water by evaporation. 2. Sodium chloride is a pure substance and cannot be separated by physical process into its chemical constituents. 3. Soft drinks are mixtures. Which of the statements given above is/are correct?

Consider the following statements regarding the properties of a compound formed by Iron and Sulphur: 1. It is black in colour. 2. It is attracted to a magnet. 3. It has a fixed composition. Which of the statements given above is/are correct?

Which one of the following is an example of an aerosol where a solid is dispersed in a gas?

Consider the following statements about 'Elements': 1. They are the basic form of matter. 2. They can be broken down into simpler substances by chemical reactions. 3. There are less than 50 known elements. Which of the statements given above is/are correct?

Consider the following pairs of Colloids and their Dispersing Medium: 1. Smoke : Gas 2. Shaving cream : Liquid 3. Jelly : Solid How many of the above pairs are correctly matched?

Which one of the following pairs is correctly matched regarding the state of dispersed phase and dispersion medium?

With reference to 'Emulsions', consider the following statements: 1. They are colloids where both the dispersed phase and dispersion medium are liquids. 2. Sponge and pumice are examples of emulsions. 3. They are heterogeneous mixtures. Which of the statements given above is/are correct?

With reference to the concentration of a solution, consider the following statements: 1. A solution is called saturated when no more solute can be dissolved in it at a given temperature. 2. The amount of solvent present in a saturated solution is called its solubility. 3. If a saturated solution is heated, it becomes unsaturated. Which of the statements given above is/are correct?

Which one of the following is an example of a heterogeneous mixture?

Which one of the following statements correctly describes the separation of mixtures?

Air is classified as a mixture rather than a compound because:

The antiseptic solution known as 'Tincture of Iodine' is prepared by dissolving: