1. What happens to idli dough when it is kept at room temperature on a summer day?

2. People living in coastal areas use plastic articles than iron articles for their day to dayactivities. Why?

3. The decomposition of vegetable matter in to compost is an example of what typeOf reaction?

4. Which term is used to indicate the development of unpleasant smell and taste in butterand oil containing food?

5. What color difference would you observe on burning a candle and a magnesium ribbon?

6. Ashok wanted his house to white washed. He bought 10kg quick lime from market and dissolved it in 30liters of water. On adding lime to water he noticed that bubbles were produced and the solution becomeshot. Give reason and name the product formed.

7. Arun took a pale green substance X in a test tube, and heated it over a flame. He observed a colorchange along with evolution of two gases with the smell of burning sulphur

(a) Identify X. (b) Identify the product formed. (c) Write the equation.

(d) Identify the type of chemical reaction.

8. Grey colored metal X is used in making dry cell. It is also used for coating iron metal toprevent it from rusting .When granules of X are added to blue solution of compound ofa reddish brown metal Y, the color of the solution gets discharged and metal Y isformed. Identify X and Y. Write the chemical reaction and identify the type ofreaction.

9. A compound X is used for drinking has pH=7.Its acidified solution in presence ofelectricity undergoes decomposition to produce gases Y andZ. The volume of Y isdouble than Z.Yis highly combustible where as Z is a supporter of combustion.Identify X,YZand write the chemical reactions involved.

10. A metal nitrate solution A is added to reddish brown metal B. The metal present inA is used for making jewellery and turns black in air, very thin foils of metal are used todecorate sweets. The compound C formed on chemical reaction is blue in color andmetal present in A is formed. Identify A B and C and write chemical reactionsinvolved.

11. Silver articles develop black coating and copper articles develop green coating.Which chemical phenomenon is responsible for this coating?

12. An aqueous solution of metal nitrate X reacts with Sodium bromide solution to .formyellow precipitate of compound Y which is used in photography. Y on exposure tosunlight, undergoes decomposition reaction to form metal present in X along with gas.Identify X and Y. Write the chemical reaction and identify the type of reaction

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