important mcq and q&a for acids,bases and salts, electric current and its effects, motion and time, nutrition in animals, weather, climate and adaptations of animals to climate please! all 7th ncert. need ASAP. good answer will be marked BRAINLIEST!
Answers
Answer:
ACIDS AND BASES
. The nature of calcium phosphate is present in tooth enamel is (a) Basic (b) Amphoteric (c) Acidic (d) Neutral 2. NaHCO, formed by reaction of (a) N a O H + H 2 C O 3 NaOH+H2CO3 (b) N a C l + H 2 C O 3 NaCl+H2CO3 (c) N a 2 C O 3 + H C l Na2CO3+HCl (d) N a O H + N a 2 C O 3 NaOH+Na2CO3 3. Calcium phosphate is present in tooth enamel. Its nature is (a) basic (b) acidic (c) neutral (d) amphoteric
4. Which of the following does not form an acidic salt? (a) Phosphoric acid (b) Carbonic acid (c) Hydrochloric acid (d) Sulphuric acid
5. The chemical formula of caustic potash is (a) N a O H NaOH (b) C a ( O H ) 2 Ca(OH)2 (c) N H 4 O H NH4OH (d) K O H KOH
6. Which one of the following is acidic? (a) Lemon juice (b) Tomatoes (c) Milk (d) All 7. An aqueous solution turns red litmus solution blue. Excess addition of which of the following solution would reverse the change? (a) Baking power (b) Lime (c) Ammonium hydroxide solution (d) Hydrochloric acid
8. Which one of the following types of medicines is used for treating indigestion? (a) Antibiotics (b) Analgesic (c) Antacid (d) Antiseptic
9. Butyric acid is found in (a) Rancid butter (b) Rancid cake (c) Stings of bees (d) All of these
10. An indicator is one kind of the following compound (a) Strong acid only (b) Reducing agent (c) Weak base or acid only (d) Complex salt
11. Assertion: Universal indicator gives green colour with distilled water. Reason: pH of distilled water is 7 and it is neutral and universal indicator gives green colour with neutral solution. (a) Both A and R are true and R is the correct explanation of A. (b) Both A and R are true but R is not the correct explanation of A. (c) A is true but R is false. (d) A is false but R is true. (e) Both A and R are false. 12. When a bee stings, immediately a paste of lime is put on the sting. Why? (a) Bee sting is made of a base (b) Bee sting contains an acid called formic acid. It gets neutralised with CaO. (c) Bee sting is acidic due to hydrochloric acid and this is neutralised (d) All of the above.
13. Sodium hydroxide turns phenolphthalein solution (a) pink (b) yellow (c) colourless (d) orange
14. PH scale of a neutral solution is (a) 14 (b) 7 (c) 10 (d) 12
15. At what temperature is gypsum heated to form Plaster of Paris? (a) 90°C (b) 100°C (c) 110°C (d) 120°C 16. Sodium carbonate is a basic salt because it is a salt of (a) strong acid and strong base (b) weak acid and weak base (c) strong acid and weak base (d) weak acid and strong base
17. What is the pH range of human body? (a) 7.0 – 7.8 (b) 7.2 – 8.0 (c) 7.0 – 8.4 (d) 7.2 – 8.4
18. Which of the following gives the correct increasing order of acidic strength? (a) Water < Acetic acid < Hydrochloric acid (b) Water < Hydrochloric acid < Acetic acid (c) Acetic acid < Water < Hydrochloric acid (d) Hydrochloric acid < Water < Acetic acid
19. Acids react with bases to form salt and water. This reaction is known as: (a) Combination (b) Decomposition (c) Neutralisation (d) reduction
20. Acids react with metals to liberate _________gas (a) Carbon dioxide (b) Carbon monoxide (c) Hydrogen (d) Water
Answer Key
1. (a) Basic
2. (a) N a O H + H 2 C O 3 NaOH+H2CO3
3. (a) basic
4. (b) Carbonic acid
5. (d) K O H KOH
6. (d) All
7. (d) Hydrochloric acid
8. (c) Antacid
9. (b) Rancid cake
10. (c) Weak base or acid only
11. (a) Both A and R are true and R is the correct explanation of A.
12. (b) Bee sting contains an acid called formic acid. It gets neutralised with CaO.
13. (a) pink
14. (b) 7
15. (b) 100°C
16. (d) weak acid and strong base
17. (a) 7.0 – 7.8
18. (a) Water < Acetic acid < Hydrochloric acid
19. (c) Neutralisation
20. (c) Hydrogen
ACID AND BASE CHAPTER COMPLETED
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