CBSE 10th Science Exam 2025-26: Important Case Study Questions with Answer- Free PDF

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This post provides science case study questions with answers for Class 10 students preparing for the CBSE Board Exams 2026. These notes are prepared according to the latest CBSE exam pattern.

In the new exam pattern, the weightage of these questions has been significantly increased. In this article, we have compiled important case study questions with answers from all chapters of Class 10 Science - Physics, Chemistry, and Biology.

These questions are based on the NCERT syllabus and previous years' papers. Regular practice of these questions will help you score well in the board exams. You can download this PDF absolutely free from the link given below!

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CBSE 10 Science Case Study Questions 2025-26 PDF

Let’s look at an example to understand how these questions appear:

Q. No.1: In early October 2021, a sudden, major energy crisis shocked India. Coal producers, distribution companies, state governments, the Union coal and power ministry and the Prime Minister’s Office were consumed by the crisis alike. This type of energy crisis will become very common in the future. This is high time we start saving energy. The electrical energy used can be decreased either by lowering the duration of consumption or by reducing the power consumption of that appliance or fixture. This will not only decrease the cost but will also result in a reduced impact on the environment. The power of an electric device determines its energy consumption per unit time. Watt is the SI unit of power. About 20% of the household power consumption is due to lightning (electric bulbs, tube lights, fancy lights, etc.), while for the commercial establishments, the power consumption due to lightning is close to 40%. LEDs use much less energy than incandescent bulbs because diode light is much more efficient, power-wise, than filament light. LED bulbs use more than 75% less energy than incandescent lighting. At low power levels, the difference is even larger. Bright LED flood lamps use only 11 to 12 watts while creating a light output comparable to a 50-watt incandescent bulb.

Based on the above information, answer the following question:

(a) What is the SI unit of electrical energy?

(b) Define one watt.

Attempt either subpart (c) or (d).

(c) A bright LED flood lamp uses 12 watts. How much energy it consumes in 5 s?

(d) An electrical appliance is connected to a 110 V supply source. The 2 A current passes through it. What is the power of the appliance?

Answer:

(a) The SI unit of electrical energy is joule (J).

(b) One watt is the power consumed by a device that carries 1 A of current

when operated at a potential difference of 1 V.

P = VI

When, V = 1 V and I = 1 A

P = 1 watt

(c) 60 J

(d) The power of the appliance is 220 W.

Case No.2: When two pairs of contrasting characters are involved in a cross, it is called a dihybrid cross. Mendel crossed a plant with yellow, round seeds with a plant with green, wrinkled seeds. All the plants in the F1 generation have yellow, round seeds. When these plants were self-pollinated, the F2 generation possessed four phenotypically different offspring.

Based on the above information, answer the following question:

(a) If a cross is made between a yellow, round-seeded plant (YyRr) with a yellow, wrinkled-seeded plant (Yyrr). What is the probability of getting a green, wrinkled-seeded plant?

(b) How many types of gametes can be produced by YyRr?

(c) What is the phenotypic ratio of a Mendelian dihybrid cross?

(d) Which law was derived from the dihybrid cross of Mendel?

Answer:

(a) The probability of getting a green, wrinkled-seeded plant (yyrr) is 1/8.

(b) Four types of gametes (YR, Yr, yR and yr) will be produced.

(c) The phenotypic ratio of a Mendelian dihybrid cross is 9:3:3:1.

(d) The law of independent assortment was derived from the dihybrid cross of Mendel.

Q.No.3: Mendeleev arranged the 63 elements known at that time in order of their ascending atomic masses and prepared a periodic table. Mendeleev's periodic table contained vertical columns called 'groups' and horizontal rows called 'periods': Elements with similar properties were placed in the same groups. The basis of Mendeleev's classification is his periodic law which states that 'the physical and chemical properties of elements are periodic functions of their atomic masses'.

Based on the above information, answer the following question:

(a) Write the main difference between Mendeleev's and Modern Periodic Law.

(b) Why was the position of hydrogen not fixed in Mendeleev's Periodic Table?

(c) Why did Mendeleev leave some gaps in his Periodic Table?

(d) Why is atomic number considered to be a more appropriate parameter than atomic mass for the classification of elements in a Periodic Table?

Answer:

(a) Mendeleev's Periodic Law depends on the atomic mass of an element, while the Modern Periodic Law depends on the atomic number of an element.

(b) Hydrogen was not given a fixed position. It was considered in group IA as well as in group VIIA because it shows the characteristics of alkali metals as well as halogens.

(c) Mendeleev left some gaps in his Periodic Table to make sure that elements with similar properties lie in the same group. These gaps were left for subsequent inclusion of the elements not known at that time. These elements were discovered later.

(d) The chemical and physical properties of elements depend upon atomic number which is the number of electrons. Therefore, the atomic number is considered to be a more appropriate parameter for the classification of elements.