A student tests three oxides $X$ , $Y$ , and $Z$ with litmus paper and records the following observations: (i) Oxide $X$ dissolves in water to turn blue litmus red. (ii) Oxide $Y$ dissolves in water to turn red litmus blue. (iii) Oxide $Z$ reacts with both dilute hydrochloric acid and sodium hydroxide solution to form salt and water. Identify the general nature (acidic, basic, or amphoteric) of oxides $X$ , $Y$ , and $Z$ . Give one example of a chemical formula for each type of oxide.

hard 5 marks Class 10 · Science · Acids, Bases and Salts

Answer

Oxide

X

is acidic (e.g.,

CO_{2}

), Oxide

Y

is basic (e.g.,

Na_{2} O

), and Oxide

Z

is amphoteric (e.g.,

Al_{2} O_{3}

The correct answer is Oxide $X$ is acidic (e.g., $CO_{2}$ ), Oxide $Y$ is basic (e.g., $Na_{2} O$ ), and Oxide $Z$ is amphoteric (e.g., $Al_{2} O_{3}$ ). — Step 3: Analyze Oxide $Z$ . Since it reacts with both acids (hydrochloric acid) and bases (sodium hydroxide) to form salt and water, it exhibits both acidic and basic behavior. Therefore, Oxide $Z$ is an amphoteric oxide. Example: Aluminium oxide ( $Al_{2} O_{3}$ ) or Zinc oxide ( $ZnO$ ).

Step-by-step solution

Step 1: Analyze Oxide $X$ . Since it turns blue litmus red, its aqueous solution is acidic. Therefore, Oxide $X$ is an acidic oxide (typically a non-metallic oxide). Example: Carbon dioxide ( $CO_{2}$ ) or Sulphur dioxide ( $SO_{2}$ ).
Step 2: Analyze Oxide $Y$ . Since it turns red litmus blue, its aqueous solution is basic. Therefore, Oxide $Y$ is a basic oxide (typically a metallic oxide). Example: Sodium oxide ( $Na_{2} O$ ) or Magnesium oxide ( $MgO$ ).
Step 3: Analyze Oxide $Z$ . Since it reacts with both acids (hydrochloric acid) and bases (sodium hydroxide) to form salt and water, it exhibits both acidic and basic behavior. Therefore, Oxide $Z$ is an amphoteric oxide. Example: Aluminium oxide ( $Al_{2} O_{3}$ ) or Zinc oxide ( $ZnO$ ).

Common mistake: Confusing amphoteric oxides (which react with both acids and bases) with neutral oxides like carbon monoxide (

CO

) or water (

H_{2} O

Concept tested: Nature of metallic, non-metallic, and amphoteric oxides

Published 24 August 2026 · Last updated 16 September 2026 · How this solution was prepared and checked

Step-by-step solution

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