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Answers
Answer:
15.b.
16. b
17 d.
18. a and B are correct but I don't know about c and d
19.
20. c.
21 a
22
23
Explanation:
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Answer:
Q 15) (b) Sour,bitter.
Q 16) (b) Blue to red.
Q 17) (d) All of above.
Q 18) (d) Methyl orange becomes
pink in basic substances
and yellow in acidic
substances.
Q 19) (b) Zinc.
Q 20) (c) Both (A) and (B).
Q 21) (b) Dilution.
Q 22) (b) NaCl.
Q 23) (d) HCl.
Q 24) (a) Calcium Oxy Chlorine.
Q 25) (d) have sour taste.
Q 26) (c) Litmus and Methyl
orange.
Q 27) (c) NaOH
Q 28) (c) Baking Soda.
Explanation:
Q 15) Acids are sour in taste whereas
bases are bitter.
Q 16) Acids changes the colour of litmus paper from Blue to red.
Q 17) ● Litmus is a natural indicator.
It is a purple dye which is extracted from a type of plant called "lichen". Blue litmus paper turns red if the substance is acidic.
Red litmus paper turns blue if the
substance is basic or alkaline. Litmus turns red in acidic solutions and blue in basic solutions.
● Turmeric is a natural indicator.
Turmeric compound is a naturally occurring yellow colour compound. It is an acid-base, yellow termeric compound which remines yellow when acidic solutions are added to it. When basic solutions such as potassium hydroxide
is added to it, the colour of yellow termeric turns to pinkish red.
● Red cabbage leaves is a natural indicator.
Red cabbage juice is considered to be an indicator because it shows us something about the chemical composition of other substances. Red cabbage contains a water-soluble pigment called anthocyanin that changes the colour when it is mixed with an acid or a base. Red cabbage juice contains a natural pH indicator that changes colour depending on the acidity of the solution.
Q 18) Methyl orange becomes yellow in basic substances and red in acidic substances.
Q 19) Zinc reacts with excess sodium hydroxide to form sodium zincate (Na2ZnO2) along with hydrogen gas. Zinc is a transition metal which shows moderate reactivity. Zinc reacts with NaOH to form sodium zincate with the evolution of hydrogen gas.
• Zn + 2NaOH --- Na2ZnO2 + H2.
Q 20) A base can be tested by both Red
litmus paper and Blue litmus paper
• When red litmus paper is dipped in basic solution the colour of red litmus paper converts into blue.
• When blue litmus Paper is dipped in
basic solution the colour of the the blue litmus Paper remains blue.
Q 21) A process of mixing of acid or base with water is called dilution.
Mixing an acid or base with water results indecrease in the concentration of ions. Such a process is called Dilution.
Q 22) The formula of common salt is NaCl.
Q 23) A solution of HCl react with zinc granules to give hydrogen gas which burns with a pop sound.
• Zn + HCl --- ZnCl2 + H2.
Q 24) Bleaching Powder's chemical formula is CaOCl2 and is called Calcium Oxychloride.
Q 25) Both curd and vinegar have sour taste.
Q 26) • The colour of blue Litmus Paper converts into red when it is dipped in acidic solution.
• The colour of methyl orange converts into red when when it is dipped in Methyl orange.
Q 27) NaOH is the strongest base among
Zn(OH)2, Mg(OH)2 and KOH.
Q 28) The discomfort caused by indigestion due to overeating can be cured by taking Baking soda.
The discomfort because of overeating
is caused by the acid that is released in the stomach and to cure it we need to
neutralize this acid. Acid can be
neutralized by using a base and baking soda is a base.