Introduction
Good afternoon everyone, and welcome to today’s chemistry tutorial.
In this session, we’ll explore general questions in practical chemistry taken from past WAEC, NECO, and JAMB examinations. The focus will be on indicators, laboratory reagents, salts, and common chemical tests.
Mastering these questions helps students prepare for practical exams and theory papers where hands-on lab knowledge is tested.
You can watch the full class in the video below:
Question 1: Color of Litmus in Alkaline Solution
Question:
The color of litmus in an alkaline solution is:
- A) Red
- B) Green
- C) Blue
- D) Yellow
Explanation
Litmus paper acts as an indicator:
- In acidic solutions, litmus turns red.
- In alkaline (basic) solutions, litmus turns blue.
Correct Answer: C) Blue
Question 2: Test for Carbon Dioxide
Question:
Which of the following is used to test for the presence of carbon dioxide?
- A) Blue litmus paper
- B) Lime water
- C) Red litmus paper
- D) Potassium dichromate
Explanation
The standard test for carbon dioxide (CO₂) is lime water. When CO₂ is bubbled through lime water, it turns milky due to the formation of calcium carbonate.
Correct Answer: B) Lime water
Question 3: Efflorescent Salts
Question:
Which of the following salts is efflorescent?
- A) Magnesium chloride
- B) Sodium trioxocarbonate decahydrate (washing soda)
- C) Calcium chloride
- D) Copper(II) tetraoxosulphate(VI) pentahydrate
Explanation
Efflorescent salts lose water of crystallization when exposed to air. Sodium trioxocarbonate decahydrate (Na₂CO₃·10H₂O) is a classic example.
Correct Answer: B) Sodium trioxocarbonate decahydrate
Question 4: Best Drying Agent for Hydrogen Gas
Question:
The best drying agent for hydrogen gas is:
- A) Calcium chloride
- B) Concentrated H₂SO₄
- C) Anhydrous copper(II) sulphate
- D) Sodium chloride
Explanation
Calcium chloride is an effective drying agent for gases like hydrogen because it removes moisture without reacting with the gas.
Correct Answer: A) Calcium chloride
Question 5: Appearance of Iodine Crystals
Question:
What is the appearance of iodine crystals?
- A) White solid
- B) Reddish-brown solution
- C) Gray solid with a shiny surface
- D) Blue-black solid
Explanation
Iodine crystals are gray solids with a shiny (lustrous) surface. They produce a purple vapor when heated.
Correct Answer: C) Gray solid with shiny surface
Question 6: Reagent for Identifying Starch
Question:
Which reagent is used to identify starch in a solution?
- A) Fehling’s solution
- B) Benedict’s solution
- C) Iodine solution
- D) Lime water
Explanation
Iodine solution reacts with starch to give a blue-black coloration, confirming the presence of starch.
Correct Answer: C) Iodine solution
Watch more educational videos and past questions: https://youtube.com/@allcbts
Conclusion
Practical chemistry focuses on hands-on laboratory techniques and chemical tests. Understanding indicators like litmus, efflorescent salts, and reagents such as iodine and lime water is essential for exam success. With consistent practice of past questions, students can easily handle the practical aspect of their chemistry exams.
Related Videos:
- Understanding Waves and Properties in Physics
- Science Questions for Junior Secondary School
- JUPEB Government Past Questions
- Biology Past Questions: Circulatory System
- English Top Past Questions: Grammar and Structure
Keywords
- Practical chemistry past questions and answers
- WAEC NECO JAMB chemistry practical solutions
- test for carbon dioxide in lime water
- efflorescent salts examples in chemistry
- iodine test for starch explanation
- color of litmus paper in acids and bases
- best drying agents for laboratory gases
- practical chemistry multiple choice questions
- appearance of iodine crystals in lab tests
- practical chemistry indicators and reagents
