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(a) Both A and R are correct and R explains A

When the pH in mouth is lower than 5.5, it means acids are formed due to food decay by bacteria in our mouth. The acid released reacts with enamel, which is made up of calcium phosphate and tooth decay starts.

Bases on dilution with water become less basic in nature and their pH decreases, (e.g. pH of strong base wrould be 14, on diluting its pH becomes below 14)

Correct answer is (a) +7

Correct answer is (b) 7 to 7.8

An acid which produces high amount of hydrogen ion in aqueous solution is called strong acid.

The reaction between acid and base produces salt and water. This reaction is called neutralization.

Properties of baking powder Uses:

(i) On heating releases CO₂ gas Baking industry 

(ii) Alkaline in nature, neutralises Antacid excess acid in stomach 

(iii) When it reacts with Soda-acid fire acid it releases CO₂ gas extinguisher which can extinguish fire.

(c) suspension of magnesium hydroxide

Chlorination process is used for killing germs in drinking water.

Here, ‘p’ means Potenz and ‘H’ means hydrogen.

Strong Acid: Hydrochloric acid is used as bathroom cleaner and sulphuric acid is used as electrolyte in battery Strong Base: Sodium hydroxide is used for making soap and potassium hydroxide is used as cleansing agent.

Bleaching powder on reaction with dilute acid gives chlorine gas which reacts with water to give nascent oxygen. 

Uses: 

(i ) Bleaching Used in bleaching cotton, wood pulp, clothes. 

(ii) Oxidising agent Used in chemical industries. 

(iii) Disinfectant To kill germs in drinking water.

Metal oxide is basic in nature thus, acid reacts with metal oxide as a neutralization reaction. 

Metal oxide + Acid → Salt + water 

e.g., CuO + 2HCl → CuCl₂ + H₂O

Uses of acids are: 

(i) In storage batteries (H₂ SO₄ ) 

(ii) As food preservative (acetic acid) 

(iii) In the preparation of baking powder (tartaric acid) 

(iv) In manufacturing of fertilizers (nitric acid) 

(v) In making PVC (Poly vinyl chloride) (Hydrochloric acid) 

(vi) As bathroom cleaner (hydrochloric acid)

Fatty acid is heated with aqueous solution of sodium hydroxide or potassium hydroxide to obtain soap. This reaction is called saponification.

(d) Na₂CO₃.10H₂O

(b) Good conductor

Correct answer is (d) KOH

Uses of salts are: 

(i) Adds taste to food (NaCl) 

(ii) In making a freezing mixture (NaCl) 

(iii) As washing soda for clothes (Na₂CO₃) 

(iv) As baking soda (NaHCO₃) 

(v) To purify water (alum, CaOCl₂) 

(vi) In making of soaps (NaCl)

Correct answer is (c) Gypsum

Chloride salts → Magnesium chloride, Calcium chloride Nitrate salts → Ammonium nitrate, Aluminium nitrate Sulphate salts → Calcium sulphate, Magnesium sulphate.

Detergent is able to show cleansing action even in hard water.

Salts can be obtained in the following ways:

(i) Acid reacts with base to give salt and water.

HCl + KOH → KCl + H₂O

acid base salt

(ii) Metals react with acids to form salt and give hydrogen gas.

Mg + 2HCl → MgCl₂ + H₂

(iii) Metallic oxide reacts with acid to form salt.

CuO + 2HCl → CuCl₂ + H₂O

The ions present in the compounds are:

(d) Na₂CO₃.10H₂O

Correct answer is (a) basic

(b) Turns red litmus into blue

(c) deliquescent

(a) Plaster of Paris

Plaster of Paris compound is used for casting plaster on a broken bone.

(c) Baking soda

Correct answer is (d) P

Correct answer is (b) Antacid

Correct answer is (c) 3/2

(b) An antacid

(b) cone. HNO₃ and conc. HCl in ratio of 1 : 3

Ant sting and Nettle leaf sting.

Bring a burning matchstick near the gas. It burns with ‘pop’ sound showing that it is hydrogen.

Hydrogen gas is liberated when active metal reacts with dilute hydrochloric acid.

Zn(s) + 2HCl (dil)→ ZnCl₂(aq) + H₂(g)

(c) 0.0001 M

Carbon dioxide (CO ) gas is evolved during the reaction. We pass this gas through lime water which turns milky because of the CO passing through it. If we keep on passing the gas through the milky lime water, it would become clear again.

(a) Citric acid – Lemon.

(b) Oxalic acid – Tomatoes.

(c) Lactic acid – Sour milk or curd.

(d) Tartaric acid – Tamarind.

Hydrochloric acid  (HCl) and Sulphuric acid (H SO ) are strong acids.

Acetic acid (CH₃COOH) and Citric acid (C₆H₈O₇) are weak acids.

Carbon dioxide gas is evolved.

(a) When dilute hydrochloric acid reacts with sodium carbonate, then sodium chloride, carbon dioxide and water are formed.

Na₂CO₃(s) + 2HCl(aq) → 2NaCl(aq) + CO₂ (g) + H₂(O)(l)

(b) CO₂ gas is liberated during the reaction. When carbon dioxide gas formed in the form of brisk effervescence is passed through lime water, it turns the lime water milky. If excess of carbon dioxide gas is passed through the milky lime water, the solution becomes clear again. This confirms the presence of carbon dioxide gas.

• Baking soda is chemically known as sodium bicarbonate. 
• On heating, sodium bicarbonate decomposes to form sodium carbonate, water and carbon dioxide (CO₂). 
• The carbon dioxide produced is released due to which the cake becomes soft and spongy. Hence, baking soda is used to make cake spongy and soft.

Calcium sulphate dihydrate; CaSO₄.2H₂O

CaSO₄.2H₂O+373K → CaSO₄.1/2H₂O+1 1/2 H₂O

CaSO₄.2H₂O-Gypsum

 CaSO₄.1/2H₂O- plaster of paris

Detailed Answer:

Chemical name of the gypsum-Calcium sulphate dihydrate Chemical formula of gypsum- CaSO₄.2H₂O When Gypsum is heated at 373 K it will plaster of paris and water.

CaSO₄.2H₂O+373K  → CaSO₄.1/2H₂O+1 1/2 H₂O

Carbon dioxide (CO₂). 

Pass this gas to lime water, it tums lime water milky

1. Magnesium chloride, Potassium chloride.

2. Sodium bicarbonate.

3. Chlorine (Cl₂) gas.

4. Sodium carbonate (Na₂CO₃).

5. CaOCl₂.

6. NaHCO₃.

7. Basic.

8. MgBr₂.

9. 800 °C.

10. Mineral halite and Himalayan rock salt.