Chapter 1 · Chemical Reactions and Equations

NCERT Class 10 Science Chapter 1 Intext Questions (Page 6)

All 3 questions of NCERT Class 10 Science Chapter 1 Intext Questions (Page 6) — Chemical Reactions and Equations — in the book's order, each with its answer and a step-by-step solution.

1. Q1
   Why should a ​magnesium ​ribbon ​be cleaned before ​burning ​in air?
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   Cleaning removes the unreactive magnesium oxide layer that stops oxygen reaching the metal, so the ribbon can burn.

   A magnesium ribbon kept in air becomes coated with a thin, dull layer of magnesium oxide ($\text{MgO}$), formed by its slow reaction with the oxygen in air. This oxide layer is unreactive and stops oxygen from reaching the metal underneath, so an uncleaned ribbon does not catch fire easily or burn properly. Rubbing the ribbon with sandpaper removes the layer and exposes fresh magnesium, which then burns readily with a dazzling white flame: $2\text{Mg}(s)+{\text{O}}_2(g)\to 2\text{MgO}(s)$.

   Step-by-step solution →
2. Q2
   Write the ​balanced ​equation for the following ​chemical reactions.

   1. (i)Hydrogen + Chlorine → ​Hydrogen chloride
   2. (ii)Barium chloride + ​Aluminium ​sulphate ​→ Barium sulphate + Aluminium chloride
   3. (iii)Sodium + ​Water → Sodium hydroxide + Hydrogen
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   The balanced equations are ${\text{H}}_2+{\text{Cl}}_2\to 2\text{HCl}$, $3{\text{BaCl}}_2+{\text{Al}}_2({\text{SO}}_4{)}_3\to 3{\text{BaSO}}_4+2{\text{AlCl}}_3$ and $2\text{Na}+2{\text{H}}_2\text{O}\to 2\text{NaOH}+{\text{H}}_2$.

   (i) ${\text{H}}_2+{\text{Cl}}_2\to 2\text{HCl}$; (ii) $3{\text{BaCl}}_2+{\text{Al}}_2({\text{SO}}_4{)}_3\to 3{\text{BaSO}}_4+2{\text{AlCl}}_3$; (iii) $2\text{Na}+2{\text{H}}_2\text{O}\to 2\text{NaOH}+{\text{H}}_2$

   Step-by-step solution →
3. Q3
   Write a balanced chemical equation with state symbols for ​the following reactions.

   1. (i)Solutions of ​barium chloride and sodium sulphate in water react to give insoluble barium sulphate ​and the ​solution of sodium chloride.
   2. (ii)Sodium hydroxide solution (in water) ​reacts with hydrochloric acid solution (in water) to produce sodium chloride solution ​and ​water.
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   The equations are ${\text{BaCl}}_2(aq)+{\text{Na}}_2{\text{SO}}_4(aq)\to {\text{BaSO}}_4(s)+2\text{NaCl}(aq)$ and $\text{NaOH}(aq)+\text{HCl}(aq)\to \text{NaCl}(aq)+{\text{H}}_2\text{O}(l)$.

   (i) ${\text{BaCl}}_2(aq)+{\text{Na}}_2{\text{SO}}_4(aq)\to {\text{BaSO}}_4(s)+2\text{NaCl}(aq)$; (ii) $\text{NaOH}(aq)+\text{HCl}(aq)\to \text{NaCl}(aq)+{\text{H}}_2\text{O}(l)$

   Step-by-step solution →