TTHE EDUTECH
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Very Short Answer Type Question [1 Mark] – The year 2012
1. How will you test for the gas that is liberated when hydrochloric acid acts with an active metal and the gas is hydrogen?
Answer-->. Bring a burning matchstick near the gas. It burns with a ‘pop’ sound showing that it is hydrogen.
Short Answer Type Questions[ll] [3 Marks] – The Year 2012
2. (1) Write the name given to bases that is highly soluble in water.? Give an example also?.
(2) How is tooth decay related to pH? How can it be prevented? give reason
(3) Why do bee stings cause discomfort and irritation? Rubbing by baking soda on the sting area gives relief. How??
Answer.--> (1) Alkali, e.g. NaOH (Sodium hydroxide).
(2) Lower the pH, more will be tooth decay. An acid reacts with Ca3(PO4)2 and causes tooth decay.
It can be restricted by brushing teeth after every meal.
(3) It is due to formic acid. Sodium hydrogen carbonate (Baking soda) neutralizes formic acid giving relief.
3. A white powder is added while baking pieces of bread and cakes to make them soft and fluffy. Write the name of the powder. Name its main components. Explain the function of each ingredient. Write the chemical reaction taking place when the powder is heated during baking?.
Answer-->. The white powder is baking powder and it consists of sodium hydrogen carbonate and tartaric acid.
Sodium hydrogen carbonate gives CO2 which makes cakes spongy and fluffy. Tartaric acid neutralizes the bitter taste due to sodium carbonate produced.
