Mensuration Class 8 important questions with answers PDF download
FAQs on CBSE Important Questions for Class 8 Maths Mensuration - 2025-26
1. What are some Higher Order Thinking Skills (HOTS) questions that could be asked from Chapter 9, Mensuration, in the CBSE Class 8 exams for 2025-26?
For the 2025-26 exams, HOTS questions in Mensuration often involve multi-step problems or real-world applications. Expect important questions such as:
- Finding the cost of painting the walls and ceiling of a room, which requires calculating the area of four walls and a rectangle.
- Calculating the number of smaller cubes that can be cut from a larger cuboid, involving a comparison of their volumes.
- Problems involving a road roller, where you must find the area covered in a certain number of revolutions by calculating its curved surface area.
- Comparing the surface areas of two different solids (e.g., a cube and a cuboid) that have the same volume to determine which requires more material.
2. What is the typical mark distribution for important questions from Mensuration in the Class 8 Maths exam?
In the Class 8 Maths exam, questions from Mensuration typically range from short answer (2 marks) to long answer (4-5 marks). A likely breakdown is:
- 2-mark questions: These usually test direct formula application, like finding the area of a trapezium or the volume of a cube given its side.
- 3-mark questions: These may require calculating the total surface area of a cylinder or a cuboid, involving a couple of steps.
- 4 or 5-mark questions: These are often application-based (HOTS), such as problems on finding the capacity of a tank, calculating the area of a complex polygon, or real-life scenarios.
3. What type of important questions can be expected on the area of a trapezium and a general quadrilateral?
For the 2025-26 session, important questions on quadrilaterals focus on applying formulas correctly. For a trapezium, expect questions where you are given the height and the lengths of the two parallel sides to find the area. A more challenging question might provide the area and ask you to find a missing side or height. For a general quadrilateral, a common important question involves being given the length of a diagonal and the lengths of the perpendiculars dropped on it from the opposite vertices to calculate the total area.
4. If a cube and a cuboid have the same volume, which one is likely to have a larger total surface area and why is this concept important?
For any given volume, the cube will always have the minimum surface area compared to any cuboid. This concept is a crucial application of Mensuration in real life. For instance, in manufacturing and packaging, companies aim to use the least amount of material to create a box that can hold a specific volume. Understanding this principle helps in designing cost-effective and resource-efficient products, making it an important concept for application-based questions.
5. What is the most common mistake students make when asked to find the surface area of a cylinder?
The most common mistake is confusing the Total Surface Area (TSA) with the Curved Surface Area (CSA). It is important to read the question carefully.
- Use the formula for CSA (2πrh) when the question asks for the area of the curved part only, like finding the area of a label on a can or the surface of a pipe.
- Use the formula for TSA (2πr(h+r)) when the question asks for the total area of a closed cylinder, including its top and bottom circular bases, like a closed storage tank. Misinterpreting this can lead to incorrect answers in 3-mark and 5-mark questions.
6. How is the area of an irregular polygon, like a pentagon, typically calculated in an exam?
As per the Class 8 syllabus, the area of an irregular polygon is found by dividing it into familiar shapes. This is a frequently asked long-answer question. The standard method is to split the polygon into several triangles and trapeziums using diagonals or perpendiculars. You then calculate the area of each smaller shape individually and add them all up to find the total area of the polygon.
7. Why is understanding the difference between volume and capacity crucial for solving important word problems from Mensuration?
Understanding the distinction between volume and capacity is vital for applying the correct formulas in word problems.
- Volume is the 3D space an object occupies (e.g., the metal of a tank), measured in cubic units like m³.
- Capacity is the quantity a hollow object can hold (e.g., water inside the tank), measured in units like litres.
8. A road roller makes 750 complete revolutions to level a road. If its diameter is 84 cm and length is 1 m, what is the area of the road? How is this solved?
This is a classic important question. To solve it, follow these steps:
- First, find the radius from the diameter (r = 84/2 = 42 cm). Ensure units are consistent by converting the length to cm (h = 1 m = 100 cm).
- Next, calculate the Curved Surface Area (CSA) of the roller using the formula 2πrh. This gives the area covered in one revolution.
- CSA = 2 × (22/7) × 42 × 100 = 26,400 cm².
- Finally, multiply the CSA by the number of revolutions to get the total area of the road: 26,400 cm² × 750 = 19,800,000 cm².
- For full marks, convert this to a more standard unit like square metres: 19,800,000 / 10,000 = 1980 m².






















