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 day activities. Why? 3. The decomposition of vegetable matter in to compost is an example of what type Of reaction? (1) (1) (1) 4. Which term is used to indicate the development of unpleasant smell and taste in butter and oil containing food? (1) (1) 6. Ashok wanted his house to white washed. He bought 10kg quick lime from market and dissolved it in 30 liters of water.
On adding lime to water he noticed that bubbles were produced and the solution becomes hot. Give reason and name the product formed. 7. change along with evolution of two gases with the smell of burning sulphur (a) Identify X. (b) Identify the product formed. (c) Write the equation. (3) 5. What color difference would you observe on burning a candle and a magnesium ribbon? (2) Arun took a pale green substance X in a test tube, and heated it over a flame. He observed a color (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 to prevent it from rusting . When granules of ‘X’ are added to blue solution of compound of a reddish brown metal ‘Y’, the color of the solution gets discharged and metal ‘Y’ is formed. Identify ’X’ and ‘Y’. Write the chemical reaction and identify the type of reaction. 9. A compound ‘X’ is used for drinking has pH=7. Its acidified solution in presence of electricity undergoes decomposition to produce gases ‘Y’ and’Z’. The volume of ‘Y’ is double than ‘Z’. ’Y’is highly combustible where as ‘Z’ is a supporter of combustion.
Identify ‘X,’Y’’Z’and write the chemical reactions involved. (3) (3) 10. A metal nitrate solution ‘A’ is added to reddish brown metal ‘B’. The metal present in ‘A’ is used for making jewellery and turns black in air, very thin foils of metal are used to decorate sweets. The compound ‘C’ formed on chemical reaction is blue in color and metal present in ‘A’ is formed. Identify A’ ‘B’ and ‘C’ and write chemical reactions involved. 11. Silver articles develop black coating and copper articles develop green coating. Which chemical phenomenon is responsible for this coating? (2) (3)
An aqueous solution of metal nitrate ‘X’ reacts with Sodium bromide solution to . form yellow precipitate of compound ‘Y’ which is used in photography. ‘Y’ on exposure to sunlight, 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 (3) ACIDS BASES AND SALTS. CHAPTER 2 1. A compound ‘X’ is an important ingredient of an antacid. It is also used in fire extinguisher. Identify ‘X’. (1) (2) (2) 2. 3. 4. Plaster of Paris should be stored in moisture proof container. Why?
When acid rain flows into rivers the aquatic lives are affected. Why? Both glucose and HCl contain hydrogen in them, but HCl shows acidic character Whereas glucose does not. Why? (2) 5.. Under what soil condition do you think a farmer would treat the soil of his field with Quicklime, slaked lime or chalk? (1) 6. A person is caused with burns while adding water into a concentrated acid. What was the reason behind it? 7. 8. Why do acids not show acidic behavior in the absence of water? What is the colour change when a stain of curry on a white cloth comes in contact with soap? And why? 9..
A colourless compound ‘x’ obtained from sea water used in daily meals is taken in a test tube . Conc. H. 2SO4 was added to the test tube. , a pungent smelling gas ‘Y’ comes out which does not affect dry blue litmus paper but turns moist blue litmus paper red. Identify ‘X’ and ‘Y’. 10. (1) (2) (2) (1) Compound ‘X’ forms enamel of teeth. It is the hardest substance of the body. It does not dissolve in water but it is corroded when PH in the mouth is below 5. 5. Write the chemical reactions involved. (2) 11. A metal is found in the lab in the form of grey colored granules. It reacts with dil.