Nature of Matter: Elements, Compounds, and Mixtures — Quiz

Q1. Priya lists the following as examples of uniform mixtures from Table 8.1. Which one is wrongly listed?

• A. Aerated water (gas in liquid)
• B. Vinegar (liquid in liquid)
• C. Sand in water (solid in liquid)
• D. Air (gas in gas)

Q2. In Activity 8.4, sugar is heated in a boiling tube. Small water droplets appear near the open end and a black residue remains. This shows that sugar

• A. Is an element
• B. Is a compound of carbon, hydrogen and oxygen
• C. Is a uniform mixture of carbon and water
• D. Has only carbon in it

Q3. Ravi brings a magnet near Sample A (mixture of iron filings and sulfur powder) in Activity 8.5. What does he observe?

• A. Both iron and sulfur particles cling to the magnet
• B. Only iron filings get attracted; sulfur is left behind
• C. Only sulfur clings; iron is unaffected
• D. Neither responds because the mixture has been heated

Q4. When dilute hydrochloric acid is added to Sample B (iron sulfide), the gas given off is colourless and smells like

• A. Rotten eggs
• B. Fresh roses
• C. Burning sugar
• D. Vinegar

Q5. Baking powder (baking soda and tartaric acid) is an example of which type of mixture by physical state?

• A. Gas and gas
• B. Liquid and liquid
• C. Solid and liquid
• D. Solid and solid

Q6. According to the chapter, only two elements exist in a liquid state at room temperature. These are

• A. Sodium and potassium
• B. Mercury and bromine
• C. Gallium and caesium
• D. Hydrogen and helium

Q7. In Activity 8.3, a few drops of dilute sulfuric acid are added to the water in the beaker before passing current. The most likely purpose is to

• A. Change the colour of water for easy observation
• B. Make the water conduct electricity for the activity
• C. React chemically with the 9 V battery terminals
• D. Prevent the gases from condensing inside the test tubes

Q8. A packet of milk is labelled 'pure'. A teacher asks the class how a scientist would classify milk. The correct answer is

• A. A pure substance — because the packet says so
• B. An element — because it is white and uniform
• C. A mixture — because it contains more than one substance
• D. A compound — because it is taken from a single source

Q9. In ancient Indian texts like the Charaka Samhita and Susruta Samhita, the name given to a mixture of two or more metals with new properties was

• A. Mishraloha
• B. Rasaratna
• C. Dhokra
• D. Tamra

Q10. Sodium is a soft, reactive metal and chlorine is a hazardous gas. They combine to form common salt that we eat every day. This best illustrates that a compound

• A. Has the same properties as its constituent elements
• B. Has properties that may differ entirely from its constituent elements
• C. Is always more reactive than its constituent elements
• D. Cannot be made from a metal and a gas

Q11. Some minerals that are pure elements and not compounds are called

• A. Compound minerals
• B. Native minerals
• C. Ores
• D. Aerogels

Q12. Dhokra art, which uses molten brass or bronze poured into a wax-and-clay mould, is an old craft mainly from

• A. Bihar and Odisha
• B. Kerala and Tamil Nadu
• C. Punjab and Haryana
• D. Gujarat and Rajasthan

Q13. The tool used to describe the quality of air, considering pollutants like particulate matter, carbon monoxide, ozone and sulfur dioxide, is the

• A. Body Mass Index
• B. Wholesale Price Index
• C. Air Quality Index (AQI)
• D. Litmus Index

Q14. Silicon and boron are described in the chapter as elements that

• A. Are typical metals
• B. Are typical non-metals
• C. Have intermediate properties between metals and non-metals (metalloids)
• D. Are not elements at all

Q15. The word equation for the reaction that turns lime water milky is: Calcium hydroxide + Carbon dioxide → ?

• A. Calcium oxide + Hydrogen
• B. Calcium carbonate + Water
• C. Calcium chloride + Oxygen
• D. Calcium sulfate + Carbon