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प्रश्न
In order to study saponification reaction, we first prepare 20% solution of sodium hydroxide. If we record the temperature of this solution just after adding sodium hydroxide flakes to water and also test its nature using litmus, it may be concluded that the process of making this solution is
(A) exothermic and the solution is alkaline
(B) endothermic and the solution is alkaline
(C) endothermic and the solution is acidic
(D) exothermic and the solution is acidic
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उत्तर
Dissolution of sodium hydroxide in water evolves large amount of heat. Thus, it is an exothermic reaction. Since sodium hydroxide is a base, its solution in water will be alkaline when tested with litmus paper (red litmus turns blue).
Hence, the correct option is A.
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संबंधित प्रश्न
For preparing soap in the laboratory we require an oil and a base. Which of the following combinations of an oil and a base would be best suited for the preparation of soap?
(a) Castor oil and calcium hydroxide
(b) Turpentine oil and sodium hydroxide
(c) Castor oil and sodium hydroxide
(d) Mustard oil and calcium hydroxide
A student adds a spoon full of powdered sodium hydrogen carbonate to a flask containing ethanoic acid. List two main observations, he must note in his note book, about the reaction that takes place. Also write chemical equation foe the reaction.
A student takes about 6 ml of distilled water in each of the four test tubes P, Q, R and S. He then dissolves an equal amount of four different salts namely, sodium chloride in 'P', potassium chloride in 'Q', calcium chloride in 'R' and magnesium chloride in 'S'. Next, he then adds 10 drops of soap solution to each test tube and shakes its contents. The test tubes in which scum (insoluble substance) is formed with soap are:
(A) P and Q
(B) Q and R
(C) R and S
(D) Q and S
When ethanoic acid reacts with sodium hydrogen carbonate, then a salt X is formed and a gas Y is evolved. Name the salt X and gas. Y Describe an activity with the help of a labelled diagram of the apparatus used to prove that the evolved gas is the one which you have named. Also write the chemical equation of the reaction involved.
Explain the following term with example.
Monomer
Explain the following term with example.
Reduction
What is the main constituent of vinegar?
State how the following conversions can be carried out:
Ethene to Ethyl alcohol.
Draw the structural diagram of:
Ethanoic acid
Reshu by mistake forgot to label the two test tubes containing Ethanol and Ethanoic acid. Suggest an experiment to identify the substances correctly? Illustrate the reactions with the help of chemical equations.
