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ICSE Class 10 Chemistry Question 20 of 23

Solved 2025 Specimen Paper ICSE Class 10 Chemistry — Question 19

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19
Question

Question 7(iii)

8.2 grams of calcium nitrate is decomposed by heating according to the equation

2Ca (NO3)2 ⟶ 2CaO +4NO2 + O2

Calculate the following:

(a) Volume of nitrogen dioxide obtained at STP

(b) Mass of CaO formed

(Atomic weights : Ca- 40, N-14, O-16)

Answer

2Ca(NO3)2⟶2CaO+4NO2+O22[(40)+2(14)+6(16)]2(40+16)4(14)+8(16)1mole=328g=112g=184=32g\begin{matrix} \text{2Ca}(\text{NO}_3)_2 & \longrightarrow & 2\text{CaO}& +&4\text{NO}_2 & +& \text{O}_2 \\ 2[(40) + 2(14) +6(16)] & & 2(40 + 16) & & 4(14)+8(16) & & 1 \text{mole} \\ = 328 \text{g} & & = 112\text{g} & & =184 & & =32 \text{g} \\ \end{matrix}

(a) 328 g of calcium nitrate liberated 4 x 22.4 lit of NO2

∴ 8.2 g of calcium nitrate liberated 4 x 22.4 x 8.2328\dfrac{8.2}{328} = 0.224 lit of NO2

(b) 328 g of calcium nitrate produces 2 x 56 g of CaO

∴ 8.2 g of calcium nitrate will produce 2 x 56 x 8.2328\dfrac{8.2}{328} = 2.8 g of CaO.