Explain the following term: 

 Precipitation reaction. 

Translate the following statement into chemical equation and then balance it. 

Carbon disulphide burns in air to give carbon dioxide and sulphur dioxide. 

Translate the following statement into a chemical equation and then balance it. 

Barium chloride reacts with aluminium sulphate to give aluminium chloride and a white precipitate of barium sulphate. 

Which of the following is not a physical change?  

Three beakers labelled as A, B and C each containing $25 \mathrm{ml}$, water were taken. A small amount of $\mathrm{NaOH}$, anhydrous ${\mathrm{CuSO}}_4$ and $\mathrm{NaCl}$ were added to the beakers A, B and C respectively. It was observed that there was an increase in the temperature of the solutions contained in beakers A and B, whereas, in the case of beaker C, the temperature of the solution falls. Which one of the following statements(s) is (are) correct? 

(i) In beakers A and B, an exothermic process has occurred. 

(ii) In beakers A and B, an endothermic process has occurred. 

(iii) In beaker C exothermic process has occurred. 

(iv) In beaker C endothermic process has occurred. 

A dilute ferrous sulphate solution was gradually added to the beaker containing acidified permanganate solution. The light purple colour of the solution fades and finally disappears. Which of the following is the correct explanation for the observation? 

Which among the following is(are) double displacement reaction(s)? 

(i) $\mathrm{Pb}+{\mathrm{CuCl}}_2\to {\mathrm{PbCl}}_2+\mathrm{Cu}$

(ii) ${\mathrm{Na}}_2{\mathrm{SO}}_4+{\mathrm{BaCl}}_2\to {\mathrm{BaSO}}_4+2\mathrm{NaCl}$

(iii) $\mathrm{C}+{\mathrm{O}}_2\to {\mathrm{CO}}_2$

(iv) ${\mathrm{CH}}_4+2{\mathrm{O}}_2\to {\mathrm{CO}}_2+2{\mathrm{H}}_2\mathrm{O}$

Which among the following statement(s) is (are) true? Exposure of silver chloride to sunlight for a long duration turns grey due to 

(i) the formation of silver by decomposition of silver chloride 

(ii) sublimation of silver chloride 

(iii) decomposition of chlorine gas from silver chloride 

(iv) oxidation of silver chloride.