CG SCERT Chhattisgarh State Board Class 7 Science (Science and Technology) Chapter 4 Acids, Bases and Salts Exercises Questions and Answers.
(1) Choose the correct answer –
The colour of phenolphthalein in as acidic medium is –
Answer:- (d) Colourless.
Formation of salt by the reaction of an acid with a base is called –
Answer:- (d) Neutralization.
Gas used to extinguish fire in a fire extinguisher is –
(c) Carbon dioxide
Answer:- (c) Carbon dioxide.
(4) The juice of raw Mango is –
(d) None of these
Answer:- (a) Acidic.
(2) Fill in the blanks –
(1) Acid are — in test.
(2) Bases are —- to touch.
(3) The nature of common salt solution is —-.
(4) Water solution bases are called —-.
(3) Make appropriate connection –
(1) Soap solution
|(2) Sugar solution||(d)||
(b) Acidic substance
(3) Litmus paper
|(a)||(c) basic substance|
|(4) Lemon juice||(b)||
(d) neutral substance
(4) Indentify true & false statements from the following & rewrite the false statement after correcting them
(a) Lemon juice changes red litmus – false
Answer:- Lemon juice changes blue litmus to red
(b) bases red rough to touch – False
Answer:- Bases are soapy to touch
(c) The function of an antacid is to increase acidity in the
Answer:- Stomach – False
– The function of an antacid is neutralise acid of from our stomach
(d) Coating of utensite prevents them from burning in fire
Answer:- False – Coating of utensite prevents them from corrosion.
(5) What is acid?
Answer:- The substance which turn blue litmus paper to red know as an acid. Ex- H2SO4, HCl
(6) How will you differentiate between an acid & a base?
Acid turn blue litmus paper red.
Base turn red litmus paper blue.
Acid are sour in test
Bases are bitter in test
Acid solution remain colourless with phenolphthalein
Base solution gives pink colour with phenolphthalein
(7) What are salts? Explain the reaction by which they are formed?
Ans. Salts is a compound which formed by the neutralising reaction between acid & an alkali.
Reaction between acid & an alkali
HCl + NaoH -> Nacl + H2O
Acid + Alkali -> Salt + water
(8) Water are antacid? What is their function?
Answer:- The substance which neutralise extra acid from our stomach is called antacid.
- Antacid give relief from sour belches.
- Antacid give relief from acidity in the stomach.
(9) Write the common & chemical names of least three salt that we use in our daily life.
|Common Name||Chemical Name|
|(1) Baking soda||– Sodium bicarbonate/NaHCO3|
|(2) Washing soda||– Sodium carbonate/Na2CO3|
|(3) Common salt||– Sodium chloride/Nacl|