Q1. Define rancidity. What kind of substances are used to prevent rancidity? Explain any three methods to prevent rancidity.
Q2. You are provided with two containers made up of copper and aluminium. You are also provided with solutions of dil. HCl, dil. HNO3 and H2O. In which of the above containers can these solutions be kept?
Q3. Write balanced chemical equations for the following reactions:
(i) NaOH solution is heated with zinc granules.
(ii) Excess of Carbon Dioxide gas is passed through lime water.
(iii) Dilute Sulphuric Acid reacts with sodium carbonate.
(iv) Egg shells are dropped in Hydrochloric Acid.
(v) Copper (II) Oxide reacts with dilute Hydrochloric Acid.
Q4. A compound ‘X’ on heating with excess Conc. Sulphuric Acid at 443 K gives an unsaturated compound ‘Y’, ‘X’ also reacts with sodium metal to evolve a colourless gas ‘Z’. Identify ‘X’, ‘Y’ and ‘Z’. Write the equation of the chemical reaction of formation of ‘Y’ and also write the role of Sulphuric Acid in the reaction.
Q5. Consider the Chemical equation given below and answer the questions that follow.
ZnO + C → Zn + CO
(a) Name the substance which is getting oxidised.
(b) Name the substance which is getting reduced.
(c) Name the oxidising agent.
(d) Name the reducing agent.
(e) What type of a reaction does this equation represent?
Q6. With the help of an activity, demonstrate how do we know that a chemical reaction has taken place?