We see that chemicals are used in each field of life. All our bio-activities are operated by chemicals; soap, detergent, beautiful clothes and various things of household consumption, which are chemical substances. Cement in making buildings, electrical apparatus, satellites, from motor vehicle up to agriculture field, everywhere chemicals are used, and theories of Chemistry are used. We use medicines when we fall ill, that is also chemical. Many types of sour-sweet substances, food preservatives are all chemical mixtures. Hence, it is true that daily life cannot be imagined without chemicals.
Here, we have provided the detailed solutions of RBSE Class 10 Science Solutions Chapter 5 to help students in clearing their doubts that they might encounter while solving the RBSE textbook questions. These solutions for Class 10 are given in an easy-to-understand way so that the students can easily comprehend the steps and the concepts mentioned here.
RBSE Class 10 Science Chapter 5: Objective Textbook Questions and Solutions
Q1. Aqueous solution of base
(A) Turns blue litmus into red
(B) Turns red litmus into blue
(C) Turns litmus solution into colourless
(D) Does not have any effect on litmus solution
Answer: B
Q2. Solutions of acid and base are …………. of electricity?
(A) Insulator
(B) Conductor
(C) Semiconductor
(D) No effect
Answer: B
Q3. pH is negative logarithm of which ions?
(A) [H2O]
(B) [OH–]
(C) [H+]
(D) [N+a]
Answer: C
Q4. What one is the pH of acidic solution?
(A) 7
(B) 14
(C) 11
(D) 4
Answer: D
Q5. In our stomach, digestion of food occurs in which medium
(A) Acidic
(B) Alkaline
(C) Neutral
(D) Variable
Answer: A
Q6. In making fire extinguisher, which substance is used
(A) Sodium Carbonate
(B) Sodium hydrogen carbonate
(C) Plaster of Paris
(D) Sodium Chloride
Answer: B
Q7. Washing soda is
(A) NaHCO3
(B) NaCl
(C) CaSO4.1/4H2O
(D) Na2CO3.10H2O
Answer: D
Q8. Which gas is released on keeping bleaching powder open in air?
(A) H2
(B) O2
(C) Cl2
(D) CO2
Answer: C
Q9. Soap works
(A) In soft water
(B) In hard water
(C) Variable
(D) None of these.
Answer: A
Q10. In micelle information, hydrocarbon tail is?
(A) Inward
(B) Outward
(C) Keeps changing
(D) Towards any direction
Answer: A
Q11. Compounds which accept proton [H+]
(A) Acid
(B) Salt
(C) None of these
(D) Base
Answer: D
RBSE Class 10 Science Chapter 5: Very Short Answer Type Questions and Solutions
Q12. Which acid is found in the sting of red ant?
Answer: Formic Acid is found in sting of red ant.
Q13. What are proton donor compounds called?
Answer: Proton donor compounds are called Acid.
Q14. What is neutralisation?
Answer: Neutralization is a chemical reaction where an acid and a base react with each other quantitatively. It is also written as Neutralisation. The acid strength of the reactant gives the pH of the neutralized solution.
To know more click the link: https://byjus.com/chemistry/neutralization/
Q15. How drinking water is made bacteria free?
Answer: Drinking water can be made bacteria free by adding Chlorine.
Q16. How acid reacts with metallic oxide? Give equation.
Answer: Metal oxides react with acid and form salt and water. These salts are basic (alkaline) in nature.
Q17. In pH, what p and H stands for?
Answer: In pH, p stands for Potenz and H stands for Hydrogen.
Q18. Which treatment would we take to get relief from excess acidity produced in stomach?
Answer: Milk of magnesia.
Q19. Name two sodium salts.
Answer: Sodium chloride and Sodium carbonate.
Q20. Give definition of base according to Lewis.
Answer: According to Lewis, base are substances that donates electron pair.
Q21. What is saponification?
Answer: Saponification is simply the process of making soaps. Soaps are just potassium or sodium salts of long-chain fatty acids. During saponification, ester reacts with an inorganic base to produce alcohol and soap. It generally occurs when triglycerides are reacted with potassium or sodium hydroxide (lye) to produce glycerol and fatty acid salt, called ‘soap’.
To read more about saponification click the link: https://byjus.com/chemistry/saponification/
Q22. What is the characteristic of detergents?
Answer: Detergents are like soap but they work in both soft and hard water. So, generally detergents are used for cleaning.
Q23. Which compound is used for plastering cracked bones?
Answer: Plaster of Paris is used for plastering cracked bones.
Q24. In a solution, concentration of hydrogen ion is 1 x 104 gm mole L-1. Find pH of solution. Tell whether solution is acidic or alkaline?
Answer: By using formula,
pH = -log [1 x 104]
pH = 4 log10
H = 4
Therefore, the solution is acidic because pH value is less than 7.
RBSE Class 10 Science Chapter 5: Short Answer Type Questions and Solutions
Q25. Write name and uses of two strong acids and two strong bases.
Answer: Strong Acid: Hydrochloric acid is used in the production of batteries, photoflash bulbs and fireworks.
Strong Base: Sodium is used to clean up spills from strong acids.
Q26. Differentiate soap and detergents?
Answer: The key differences between soaps and detergents are tabulated below.
| Difference Between Soap and Detergent | |
| Soaps | Detergents |
| Consist of a ‘-COONa’ group attached to a fatty acid having a long alkyl chain. | Consist of a ‘-SO3Na’ group attached to a long alkyl chain. |
| They are not effective in hard water and saline water | They do not lose their effectiveness in hard water and saline water. |
| Soaps are completely biodegradable | Detergents containing a branched hydrocarbon chain are non-biodegradable |
| They have a tendency to form scum in a hard water environment. | These compounds do not form scum. |
| They are derived from natural sources such as vegetable oils and animal fats. | Detergents are synthetic derivatives. |
| Soaps are environment-friendly products since they are biodegradable. | These compounds can form a thick foam that causes the death of aquatic life. |
| Examples of soaps: sodium palmitate and sodium stearate. | Examples of detergents: deoxycholic acid and sodium lauryl sulfate. |
To read more click the link: https://byjus.com/chemistry/difference-between-soap-and-detergent/
Q27. Write definitions of acid and base according to Arrhenius.
Answer: Definition of acid and base was at first given by Arrhenius in 1887. Those substances which give hydrogen ion (H+) when decompose in water are called acids and those substances that decompose in water and give hydroxyl ion (OH–) are called bases.
Q28. What is pH? Describe pH range of acidic and alkaline solution.
Answer: pH is defined as the measure of hydrogen ion concentration which is used for measuring the acidity or alkalinity of a given solution. The range of the pH scale is 0 to 14. pH value 7 is considered to be neutral while the values that are less than 7 are acidic in nature and the values more than 7 are basic in nature.
Q29. What is water of crystallisation? Give example.
Answer: Crystalline salts frequently contain water in two different states of combination, which are distinguished by the terms water of constitution (or sometimes basic water, or water of hydration), and water of crystallization. The water of crystallization is much less intimately combined with the salt than the water of the constitution and is, therefore, more easily expelled.
The reason for applying the term water of crystallization is the portion of combined water which is most easily expelled, is found in the influence which exerts upon the crystallization of the salt. Some substances are capable of forming crystals with different proportions of water of crystallization.
For example, when anhydrous copper sulfate, a white powder is dissolved in water and the solution is set aside to crystallize, the product consists of blue prisms of copper sulfate pentahydrate.
For more information related to the concept click the link: https://byjus.com/questions/what-is-water-of-crystallization/
Q30. What happens when:
(i) Curd or sour substances are kept in metal utensils.
(ii) Teeth are not cleaned after eating food at night.
Answer (i): Curd or sour substance has acid in it. The acid reacts with metal to produce hydrogen gas. Hence, any sour substance gets spoiled and damages the metallic container if it is kept in a metallic container.
Answer (ii): Generally pH of mouth is almost 6.5. Bacteria present in the mouth reduce pH of mouth when they react with food remains in teeth by producing acid. Tooth enamel decay when pH value becomes lower than 5.5. So, after eating food, teeth should be cleaned by toothpaste or alkaline solution so that tooth decay can be controlled.
Q31. A compound A reacts with acid H2SO4 and release gas B with brisk effervescence. On heating gas B burns with pop sound. Tell names of A and B and give equation of reaction.
Answer: Substance A is a metal (example: Zinc) and gas B is hydrogen gas. The reaction can be shown by the following equation.
Zn + H2 SO4 → ZnSO4 + H2
Q32. Write the properties and uses of Plaster of Paris?
Answer: The properties and uses of Plaster of Paris are as follows:
Properties:
- It is a white sleek solid substance
- On mixing in water for 15 to 20 minutes, it becomes hard and solid
2CaSO4.¼ H2O + 3H2O → 2CaSO4. 2H2O
Uses:
- Its most important use is in making plaster for repairing cracked bones.
- In making buildings.
- In dental medicals.
- In making decorative materials like statues.
- As fire extinguisher substances.
Q33. Write the properties and uses of Washing Soda?
Answer: The properties and uses of Washing Soda are as follows:
Properties:
- It is white crystalline solid
- Soluble in water
- Its solution in water is alkaline’
- On heating, its crystal loses water and get converted into soda ash
Uses:
- In washing and cleaning
- In formation of caustic soda, baking soda, glass, soap borax
- As detergent
- In paper, paint and textile industry
- As laboratory reagent
Q34. Write the properties and uses of Baking Soda?
Answer: The properties and uses of Baking Soda are as follows:
Properties:
- It is white crystalline solid.
- It is hardly soluble in water
- Its solution in water is alkaline.
- CO2 gas is released on heating it
2NaHCO3 → Na2CO3 + H2O + CO2
Uses:
- As baking powder in food products
- In making soda water and soda containing cold drink
- As antacid to remove acidity of stomach
- As mild antiseptic
- In fire extinguishers
- As laboratory reagent.
Q35. Write the properties and uses of Bleaching Powder?
Answer: The properties and uses of Bleaching Powder are as follows:
Properties
- It is a yellow solid substance with sharp smell
- It is soluble in cold water
- It gives chlorine gas when kept open in air
- It gives chlorine gas on reacting with dilute acids
- Chlorine gas which is released from bleaching powder react with water and form nascent atomic oxygen [O]. This oxygen perform bleaching reaction and behave as an oxidizing agent.
Uses:
- It is used for bleaching dirty clothes in the laundry, as a bleaching agent for cotton and linen in the textile industry.
- It is a strong oxidizing agent hence, used as an oxidizer in many industries.
- It is used as a disinfectant which is used for disinfecting water to make potable water.
Q36. Write the properties and uses of Sodium Chloride?
Answer: The properties and uses of Sodium Chloride are as follows:
Properties
- It is white solid substance
- Its melting point is high 1081 K
- It is highly soluble in water
- It gets ionised in aqueous solution.
Uses:
- It is used in medicine – Saline solution in nasal spray
- It is used in fire extinguishers
- It is used in cleansers like shampoo, toothpaste
- It is used in the soda ash industry to produce sodium carbonate through Solvay process
- It is used in the paper industry, textile industry and in the construction of roads
- It is used in water softening.
Q37. Write the properties and uses of Sodium Hydroxide?
Answer: The properties and uses of Sodium Hydroxide are as follows:
Properties
- Sodium Hydroxide in its pure form is a white crystalline solid.
- It is odourless.
- It is soluble in water, glycerol and ethanol. When solid sodium hydroxide is mixed with water it results in a highly exothermic reaction.
- Has a higher viscosity than water about 78 mPas.
- It can form several hydrates.
- It can rapidly absorb carbon dioxide and water from the air. It can also exist in the form of a liquid.
- It has an ionic bond.
- It can react with protic acids to form water and salts.
- It has high acidity of 13.
Uses
- Production of soaps.
- Pulp for paper.
- Is an important laboratory chemical.
- Used in production of various other chemicals.
- Textile industry.
- Water treatment (converting hard to soft water).
- Making of glass
RBSE Class 10 Science Chapter 5: Essay Type Questions and Solutions
Q38: Explain acid and base according to Bronsted Lowry and Lewis.
Answer: Bronsted Lowry concept of acids and bases.
According to Bronsted – Lowry Acids are proton donors and base are proton acceptor. For more information related to Bronsted Lowry concept click the link: https://byjus.com/jee/acid-and-base/
Lewis Concepts of acids and bases
Acids are substances which accept electron pair and base are substances that donates electron pair. For more information related to Bronsted Lowry concept click the link: https://byjus.com/jee/acid-and-base/
Q39. Write uses of pH in normal life?
Answer: Importance of pH in daily life are as follows:
Acidity in stomach – In this problem, stomach faces pain and irritation. In this, gastric juice having more amount of hydrochloric acid is formed in our stomach which causes pain and burning sensation. To get rid of it, antacid which means weak bases like [Mg(OH)2) milk of magnesia are used. It neutralizes excess amount of acid in our stomach.
Tooth decay – Generally pH of mouth is almost 6.5. Bacteria present in the mouth reduce pH of mouth when they react with food remains in teeth by producing acid. Tooth enamel decay when pH value becomes lower than 5.5. So, after eating food, teeth should be cleaned by toothpaste or alkaline solution so that tooth decay can be controlled.
Stung of Insects – Honey-bee, ant, etc. insects have stings, which when they bite us, they release acid which comes in contact with our skin. Due to this acid, skin feels pain and burning sensation. If at that time alkaline salts like sodium hydrogen carbonate (NaHCO3) are used at that place, then effect of acid will get neutralized.
Acid Rain – Rainwater is considered pure but due to pollutents, its pH is lowering these days. This type of rain is called acid rain. This rain water affects rivers and soil also. In this way, crop, animal and even whole ecological system is affected. On controlling pollutants, acidic rain can be controlled.
pH of soil – By determining the pH of soil, the crops that can be sown in soil can be selected and use of proper fertilizer can also be determined so that good crop is obtained.
Q40. Write name, method of preparation and uses of
(i) NaOH
(ii) NaHCO3
(iii) Na2 CO3 .10H2 O
(iv) CaOCl2
(v) CaSO4 .1/2H2 O
Answer i: Sodium hydroxide
Method of Production – This is made by chlor-alkali process. Aqueous solution of sodium chloride (brine) is electrolysed to obtain NaOH.
2 NaCl + 2 H2O NaOH + Cl2 + H2
Uses: It is used for making paper, soap, detergents and artificial fibres.
Answer ii: Sodium bicarbonate or baking soda Method of Production: It is made by reaction between sodium chloride, ammonia, carbon dioxide and water.
NaCl + H2O + CO2 + NH3 → NH4Cl + NaHCO3
Uses: It is used as antacid, in soda-acid fire extinguisher and for making baking powder.
Answer iii: Washing Soda
Method of Preparation: When baking soda is heated, we get sodium carbonate. It is then crystallized by adding water.
2 NaHCO3 → Na2CO3 + H2O + CO2
Na2CO3 + 10 H2O → Na2CO3 . 10 H2O
Uses: It is used in making glass, paper, soap, borax. It is used as a cleansing agent. It is used for removing permanent hardness from water.
Answer iv: Bleaching powder
Method of Production: It is made by action of chlorine on dry slaked lime.
Ca(OH)2 + Cl2 → CaOCl2 + H2O
Uses: It is used for bleaching cotton, linen, wood pulp, etc. It is used as an oxidizing agent in the chemical industry. It is used for disinfecting drinking water.
Answer v: Plaster of Paris
Method of Production: This is made by heating gypsum.
2CaSO4 .2H2O 2CaSO4 . 1/2H2O+ 3H2O
Uses: Used for making plaster cast over fractured bones. Used for making artifacts, false ceilings, etc.
Q41. How are micelles formed? Write mechanism also.
Answer: Soap and detergent perform cleansing action by micelles formation. Firstly, soap molecules like sodium stearate are ionised in water.
This hydrocarbon tail (R) which is hydrophobic and polar end which is hydrophillic makes such structure. These parts are arranged such that hydrocarbon part is inward and negatively charged polar end is outward. It is called micelle.
Most of the impurities like oil drop etc are insoluble in water but soluble in hydrocarbon. In cleaning by soap, soap molecules from micelles around impurity. In this, hydrophobic hydrocarbon part attracts impurity and hydrophillic polar part is outward. So, impurity is surrounded and micelle is formed. Polar end present at outer ends are attracted by water and whole impurity is pulled in water.
All micelles are negatively charged (uniformly) so that they do not precipitate. That’s why when dirty clothes are treated with soap and then dipped in water, whole impurity of cloth comes out in the water.
Comments