Exploring Substances: Acidic, Basic, and Neutral — Quiz

Q1. Which of the following groups, as per the chapter, contains only acidic substances?

• A. Lemon juice, amla juice, tamarind water, vinegar
• B. Soap solution, baking soda, lime water
• C. Tap water, sugar solution, salt solution
• D. Lemon juice, soap solution, sugar solution

Q2. Ashwin lists soap solution, baking soda solution, lime water and washing powder solution. The chapter classifies this set as

• A. Acidic substances
• B. Neutral substances
• C. Basic substances
• D. Olfactory substances

Q3. Sangita tests tap water, sugar solution and salt solution with both blue and red litmus paper. According to the chapter, the colours of both papers will

• A. Both turn red
• B. Both turn blue
• C. Remain unchanged in both papers
• D. Turn green in both papers

Q4. The chapter says that litmus shows different colours in acidic and basic solutions; therefore it is called

• A. An olfactory indicator
• B. An acid-base indicator
• C. A neutralising agent
• D. A synthetic dye

Q5. The Holistic Lens box in the chapter notes that lichens, the source of litmus, are formed by the association of

• A. Two algae
• B. A fungus and an alga
• C. A fungus and a moss
• D. Two fungi

Q6. From Activity 2.2 the chapter generalises that substances which

• A. Taste bitter usually contain acids
• B. Taste sour tend to contain acids
• C. Smell sweet always contain bases
• D. Feel rough always contain bases

Q7. Lakshmi reads that bases generally taste bitter and concludes that karela (bitter gourd), which tastes bitter, must be basic. The chapter would say her reasoning is

• A. Correct, since all bitter things are basic
• B. Correct, since vegetables are mostly basic
• C. Incorrect, because karela is bitter but is not basic in nature
• D. Incorrect, because karela is acidic in nature

Q8. Sangita rubs baking soda solution between her fingers and finds it feels soapy or slippery. The chapter explains this is because

• A. All liquids feel slippery
• B. Baking soda contains a strong acid
• C. Basic substances are generally slippery to touch
• D. Baking soda is a neutral substance

Q9. While preparing the red rose indicator, Keerthi wonders why the petals are crushed and soaked in hot water. The best reason is

• A. To release the pigment from the petals into the water for use as the extract
• B. To kill the bacteria on the petals
• C. To change the petals from red to green
• D. To make the petals soluble in cold water later

Q10. Which of the following plant materials does the chapter suggest can be used to prepare a natural acid-base indicator, like the red rose extract?

• A. Wheat flour and rice
• B. Mustard oil and salt
• C. Beetroot, purple cabbage, jamun and red hibiscus (gudhal)
• D. Onion and potato peel

Q11. A curry stain on a white shirt turns red when soap is applied. From the turmeric-indicator activity, this happens because

• A. Soap is acidic and turns turmeric red
• B. Soap is basic and turns turmeric (in the curry) from yellow to red
• C. Curry contains red rose extract
• D. The shirt is dyed with litmus

Q12. On adding lemon juice or tap water to turmeric paper, the paper

• A. Turns red in both cases
• B. Turns red only with lemon juice
• C. Remains yellow in both cases
• D. Turns green only with tap water

Q13. Along with salt and water, what else is produced during a neutralisation reaction?

• A. Light is given out
• B. Heat is evolved
• C. Oxygen gas is released
• D. Carbon dioxide is released

Q14. A farmer in Rampur finds that excessive use of chemical fertilisers has made his soil acidic and his plants are not growing well. The chapter's remedy is to add

• A. More acidic fertiliser
• B. Common salt
• C. Lime, which is a base
• D. Sugar solution

Q15. The chapter's 'Know A Scientist' box describes which scientist as the 'Father of Modern Indian Chemistry'?

• A. C.V. Raman
• B. Homi Bhabha
• C. Jagadish Chandra Bose
• D. Acharya Prafulla Chandra Ray