📚 CBSE Grade-10 Study Guide
HomeScience (086)

Science (086) — CBSE Class 10 board question

Q1. [1] § 3.2 CHEMICAL PROPERTIES OF METALS § 3.3 HOW DO METALS AND NON-METALS REACT? § 3.4 OCCURRENCE OF METALS
When 2 mL of sodium hydroxide solution is added to few pieces of granulated zinc in a test tube and then warmed, the reaction that occurs can be written in the form of a balanced chemical equation as :
  1. (a) NaOH + Zn → NaZnO₂ + H₂O
  2. (b) 2NaOH + Zn → Na₂ZnO₂ + H₂
  3. (c) 2NaOH + Zn → NaZnO₂ + H₂
  4. (d) 2NaOH + Zn → Na₂ZnO₂ + H₂O
Previously asked in CBSE board exam
2024 31/1/1 Q1
Generated by claude-sonnet-4-6 · 2026-06-14 10:28 · grounding rag
Model Answer

(b) 2NaOH + Zn → Na₂ZnO₂ + H₂

This is the correctly balanced equation, with sodium zincate and hydrogen gas as products.

Source: Chapter 2, Section 2.1.2 (Activity 2.4)

Explanation

The textbook (Activity 2.4) explicitly gives this equation: 2NaOH(aq) + Zn(s) → Na₂ZnO₂(s) + H₂(g). Check balance: Na=2, O=2, H=2+2=4 on LHS; Na=2, Zn=1, O=2, H=2 on RHS — all atoms balance. Option (b) is the only choice that is both correctly balanced and has the right products (Na₂ZnO₂ + H₂).

If a question refers to an image, map, graph or diagram that is not shown here, find the actual CBSE question paper on the CBSE website: cbse.gov.in.
Previous-year CBSE Grade 10 board exam questions, organised by subject and chapter, each with a model answer — free to read and print.