Give an example of an exothermic reaction.

Give reason why do chips manufacturers usually flush bags of chips with a gas such as nitrogen. 

F, Cl and Br are the elements each having seven electrons in its valence shell. Which of these (i) has the largest atomic radius (ii) is most reactive. Justify your answer stating a reason for each. 

Write an equation for decomposition reaction when energy is supplied in the form of heat.

Identify the substance oxidised, substance reduced, oxidising agent and reducing agent in the following reaction. 

$\mathrm{CuO}+{\mathrm{H}}_2\to \mathrm{Cu}+{\mathrm{H}}_2\mathrm{O}$

Write the chemical name and formula of washing soda. How is it prepared? Write balanced chemical equation of the reaction.