NIOS Class 10 Science and Technology Chapter 1 Solution - Chemical Reaction and Equations

 Class X

 Chapter 1 – Chemical Reactions and Equations 

NIOS Class 10 Science & Technology Chapter 1 Solution

Board	NIOS
Class	10th  (Secondary)
Subject	Science and Technology (212)
Topic	Question Answer, Solution, Notes

Science

 Answer  (a) Hydrogen gas and iron chloride are produced. The reaction is as follows: 

Question

 4: What is a balanced chemical equation? Why should chemical equations be balanced? 

Answer 

A reaction which has an equal number of atoms of all the elements on both sides of the chemical equation is called a balanced chemical equation. The law of conservation of mass states that mass can neither be created nor destroyed. Hence, in a chemical reaction, the total mass of reactants should be equal to the total mass of the products. It means that the total number of atoms of each element should be equal on both sides of a chemical equation. Hence, it is for this reason that chemical equations should be balanced. 

Question 

5: Translate the following statements into chemical equations and then balance them.

 (a) Hydrogen gas combines with nitrogen to form ammonia. 

(b) Hydrogen sulphide gas burns in air to give water and sulphur dioxide. 

(c) Barium chloride reacts with aluminium sulphate to give aluminium chloride and a precipitate of bariu sulphate. 

(d) Potassium metal reacts with water to give potassium hydroxide and hydrogen gas. 

Answer 

Question

 6: Balance the following chemical equations. 

Answer

Question 

7: Write the balanced chemical equations for the following reactions.

 (a) Calcium hydroxide + Carbon dioxide →  Calcium carbonate + Water 

(b) Zinc + Silver nitrate →  Zinc nitrate + Silver 

(c) Aluminium + Copper chloride →  Aluminium chloride + Copper 

(d) Barium chloride + Potassium sulphate →  Barium sulphate + Potassium chloride 

Answer

Question 

8: Write the balanced chemical equation for the following and identify the type of reaction in each case.

 (a)Potassium bromide (aq)  + Barium iodide (aq) →  Potassium iodide (aq)  + Barium bromide(s) 

(b) Zinc carbonate (s) →  Zinc oxide (s)  + Carbon dioxide (g) 

(c) Hydrogen (g) + Chlorine (g) →  Hydrogen chloride (g)

(d) Magnesium (s) + Hydrochloric acid (aq) →  Magnesium chloride (aq) + Hydrogen (g)

Answer 

Question

 9: What does one mean by exothermic and endothermic reactions? Give examples.

 Answer 

Chemical reactions that release energy in the form of heat, light, or sound are called exothermic reactions. Example: Mixture of sodium and chlorine to yield table salt  

In other words, combination reactions are exothermic. Reactions that absorb energy or require energy in order to proceed are called endothermic reactions. For example: In the process of photosynthesis, plants use the energy from the sun to convert carbon dioxide and water to glucose and oxygen. 

Question 

10: Why is respiration considered an exothermic reaction? Explain. 

Answer 

Energy is required to support life. Energy in our body is obtained from the food we eat. During digestion, large molecules of food are broken down into simpler substances such as glucose. Glucose combines with oxygen in the cells and provides energy. The special name of this combustion reaction is respiration. Since energy is released in the whole process, it is an exothermic process. 

Question 

18:Why do we apply paint on iron articles?

 Answer

 Iron articles are painted because it prevents them from rusting. When painted, the contact of iron articles from moisture and air is cut off. Hence, rusting is prevented their presence is essential for rusting to take place. 

Question 

19: Oil and fat containing food items are flushed with nitrogen. Why?

 Answer 

Nitrogen is an inert gas and does not easily react with these substances. On the other hand, oxygen reacts with food substances and makes them rancid. Thus, bags used in packing food items are flushed with nitrogen gas to remove oxygen inside the pack. When oxygen is not present inside the pack, rancidity of oil and fat containing food items is avoided. 

Question 

20: Explain the following terms with one example each. 

(a) Corrosion

 (b) Rancidity Answer  

(a) Corrosion: 

Corrosion is defined as a process where materials, usually metals, deteriorate as a result of a chemical reaction with air, moisture, chemicals, etc. For example, iron, in the presence of moisture, reacts with oxygen to form hydrated iron oxide. 

This hydrated iron oxide is rust. (b) Rancidity: The process of oxidation of fats and oils that can be easily noticed by the change in taste and smell is known as rancidity. For example, the taste and smell of butter changes when kept for long. Rancidity can be avoided by: 1. Storing food in air tight containers 2. Storing food in refrigerators 3. Adding antioxidants 4. Storing food in an environment of nitrogen