Class 10 Acids Bases and Salts NCERT

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NCERT Textual Solved Questions

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MCQs

Q1: The most commonly used indicator in the laboratory is
(a) Methyl Orange
(b) Litmus
(c) Phenolphthalein
(d) Universal Indicator

Answer:  Universal Indicator

Q2: Olfactory indicators are:
(a) Clove
(b) Turmeric
(c) Soap
(d) Rose Petals

Answer: (a) Clove

Q3: An element common to all acids is
(a) Chlorine
(b) Nitrogen
(c) Oxygen
(d) Hydrogen

Answer: (d) Hydrogen

Q4: Metal carbonate on reaction with dilute acid release
(a) CO2
(b) CO
(c) H2O
(d) H2

Answer:  (a) CO2

Q5 (Teachers FA manual): ln general, salts
(a) are ionic compounds
(b) contain hydrogen ions
(c) contain hydroxide ions
(d) turn litmus red

Answer:  (a) are ionic compounds

Q6: On passing excess of CO2 gas in an aqueous solution of calcium carbonate, milkiness of the solution
(a) persists
(b) fades
(c) deepens
(d) disappears

Answer: (b) fades

Q7(FA manual): When magnesium and hydrochloric acid react, they produce
(a) Oxygen and magnesium chloride
(b) Chlorine and magnesium oxide
(c) Hydrogen and magnesium chloride
(d) Hydrogen and magnesium oxide

Answer: (c) Hydrogen and magnesium chloride

Q8:  Dissolution of acid or base in water is 
(a) Exothermic
(b) Endothermic
(c) Violent
(d) None of these

Answer: (a) Exothermic

Q9: Water contains more H+ ions than OH- ions. In this case, water is

(a) neutral
(b) basic
(c) acidic
(d) cannot say.

Answer:  (c) acidic

Q10: When an acid reacts with a base what compounds are formed?
(a) water only
(b) metal oxides only
(c) a salt only
(d) salt and water

Answer: (d) salt and water

Q11: Which of the following is a property of an acid? (a) slippery feel
(b) non-reactive
(c) sour taste
(d) strong colour

Answer: (c) sour taste

Q12: On diluting an acid concentration of H+ per unit volume
(a) increases
(b) decreases
(c) remains unaffected
(d) depends on the type of acid used.

Answer: (b) decreases

Q13: What is pH?
(a) the positive logarithm of the hydroxide ion concentration
(b) the positive logarithm of the hydrogen ion concentration
(c) the negative logarithm of the hydroxide ion concentration
(d) the negative logarithm of the hydrogen ion concentration

Answer: (d) the negative logarithm of the hydrogen ion concentration

Q14: Tartaric acid is the constituent of
(a) bleaching powder
(b) baking powder
(c) washing powder
(d) plaster of Paris

Answer:  (b) baking powder

Q15: A solution turns blue litmus red. Its pH value is likely to be
(a) 4
(b) 7
(c) 9
(d) 12

Answer:  (a) 4

Q16: What is the name of  H2SO3?
(a) Sulphuric Acid
(b) Sulphurous Acid
(c) Sulphite Acid
(d) Hydrogen Sulphide.

Answer: (b) Sulphurous Acid

Q17: Which gas is produced by the reaction of a base with metal?
(a) Carbon dioxide
(b) Dioxygen
(c) Dihydrogen
(d) Dinitrogen

Answer: (c) Dihydrogen

Q18: Acid + Metal-oxide  →?
(a) Base + Water
(b) Salt + Water
(c) Base + Salt
(d) Metal + Salt

Answer: (b) Salt + Water

Q19: Which of the following is a weak acid?
(a) Hydrochloric Acid
(b) Nitric Acid
(c) Acetic Acid
(d) Sulphuric Acid

Answer:   (c) Acetic Acid

Q20: An indicator is what type of compound?
(a) reducing agent
(b) strong base or acid
(c) weak base or acid
(d) salt

Answer: (c) weak base or acid

Q21: Which of the following is strong acid?
(a) Acetic acid
(b) Citric acid
(c) Nitric acid
(d) Oxalic acid

Answer: (c) Nitric acid

Q22: Name the organic acid present in tomato
(a) Tartaric Acid
(b) Malic Acid
(c) Lactic Acid
(d) Oxalic Acid

Answer: (d) Oxalic Acid

Short Answer Type Questions

Question 1.: How does baking powder differ from baking soda?

 Answer: Baking soda is a single compound which has sodium hydrogen carbonate which is alkaline (basic) in nature Baking powder is a mixture of sodium hydrogen carbonate and a mild edible(eatable) acid such as tartaric acid. When baking powder mixes with water, then the sodium hydrogen carbonate reacts with tartaric acid to evolve carbon dioxide gas which gets trapped in the wet dough and bubbles out slowly making the cake to rise and hence ‘soft and spongy’.The equation which takes place can be shown as:

NaHCO3 + H+ —-> Na+ + CO2 + H2O

Q2.: What will happen if heating is not controlled while preparing the Plaster of Paris from gypsum?

 Answer: It may be noted that the temperature should be controlled carefully. It should not be allowed to rise above 152°C (425K) because, if the whole of the water is lost then anhydrous calcium sulphate is produced, which is called dead burnt plaster and it does not have the properties of Plaster of Paris.

Q3. : What are the two main ways in which common salt (sodium chloride) occurs in nature? How is common salt obtained from seawater? Explain.

 Answer: Salt exists in two forms in nature i.e. in seawater and in the form of Halite a mineral rock of common salt. Common salt can be prepared by evaporation of seawater. Seawater is collected in the division of land and it is allowed to evaporate under sunlight. Water is evaporated leaving behind mixtures of salt, from which common salt is separated by dissolving it in suitable reagent and then, recrystallizing salt from the solution.

Q.4. : Why the aqueous solution of sodium carbonate is basic in nature? Answer: Sodium bicarbonate is an amphoteric compound. Aqueous solutions are mildly alkaline due to the formation of carbonic acid and hydroxide ion: NaHCO− 3 + H2O → H2CO3 + OH

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