- CBSE Class 10 and 12 exams start February 17, ending March 10 and April 9 respectively
- Class 10 Science paper now has three sections: Biology, Chemistry, and Physics
- Sample questions cover plant excretion, heart chambers, food webs, and genetic crosses
The CBSE Class 10 and Class 12 board examinations will begin on February 17. The Class 10 exams will end on March 10, while Class 12 exams will conclude on April 9. Ahead of the board exams, CBSE released a circular notifying about crucial changes in the paper pattern of Class 10 Science and Social Science. As per the new pattern, the question paper will have sections based on subject categories. For Science, the question paper has been divided into three sections i.e. Section A, Section-B and Section-C. Section-A is Biology, Section-B is Chemistry and Section C is Physics.
Here are some of the questions from Social Science sample paper based on new format.
Section A Biology
Q) Unlike animals, plants do not have any excretory products as they do not eat food. Comment upon the statement with justification.
Q) How many chambers are there in the heart of the following organisms? How is mixing of oxygenated and deoxygenated blood prevented in their body?
(i) Fishes
(ii) Humans
OR
Q) Explain the mechanism by which the water is transported in plants?
Q) About 100 acres of forest land was declared as Natural reserve park. The following organisms were predominant in the Natural reserve park: rabbit, frog, grass, fish, fox, water insects, zebra, peacock, snake, trees, bird, owl, insects, tiger, vulture, duck. Create a food web comprising two separate food chains with different producers by using the above data.
Q) Draw and explain how the nerve cells help in transmission of impulses?
Q) In a genetic experiment, plants with pure round green seeds (RRyy) were crossed with plants with wrinkled yellow seeds (rrYY). (i) Show the gametes formed when F1 was self-pollinated. (ii) A total of 144 seeds were produced which developed into saplings. Show the ratio in which these traits are independently inherited in these144 sapling.
Q) Neha consumed boiled sweet potatoes and boiled eggs for breakfast. Help her to understand some steps in the process of digestion of the food taken by her by answering the questions given below.
Q)Which of these food items is rich in proteins? In which part of the alimentary canal is the digestion of this component initiated? Name the enzymes, conditions required and the glands associated with the digestion here.
Q) Puneet wanted to grow banana plants.
(i) Based on your knowledge on plant reproduction should he opt for seeds or any alternate method of reproduction. Justify your answer.
(ii) Offsprings of a banana plant usually show very little variation. What causes variation and are variations good or bad? Justify.
OR
Q) Annie was conducting research on the number of fruits produced by watermelon under different conditions. She grew 25 watermelon plants each in both glass house A and B. She introduced pollinators in glass house A only.
(i) What difference will she observe in the number of fruits produced in the two glass houses? Explain with reason.
(ii) List 3 changes that will occur in a flower once it gets fertilized.
Section B Chemistry
Q) An element 'X' is stored in kerosene, and cannot be extracted from its ore using a reducing agent. 'X' forms an ionic compound on reaction with chlorine.
(i) Can we store 'X' in water? Give reason to support your answer.
(ii) Identify element 'X'. Name the process used and write the equation for extraction of 'X' from its ore.
OR
Q) The domes of many building in Europe are made of copper. These domes now appear greenish in colour.
(i) Why do the domes appear greenish though copper is orange-red in colour?
(ii) In your opinion, should the copper domes be replaced by iron domes to overcome the problem of change of colour of copper domes?
(iii) Domes used to be made from thin sheets of metals. Why did the ancient architects use copper to make domes?
Sara took 2 mL of dilute NaOH solution in a test tube and added two drops of phenolphthalein solution to it. The solution turned pink in colour. She added dilute H2SO4 to the above solution drop by drop until the solution in the test tube became colourless. 40 drops of dilute H2SO4 were used for the change in colour from pink to colourless. When Sara added a drop of NaOH to the solution, the colour changed to back to pink again. Sara now tried the activity with different volumes of NaOH and recorded her observation in the table given below:
Q) Answer the following questions based on the above information:
A. If Sara used concentrated H2SO4 in place of dilute H2SO4, how many drops will be required for the change in colour to be observed?
(a) 40 (b) < 40 (c) >40 Justify your answer.
B. Sara measured 20 drops of dil. H2SO4 and found its volume to be 1 mL. If Sara observed a change in colour of NaoH solution by using 3 mL of H2SO4, how many mL of NaOH did she add to the test tube initially?
OR
Sara takes 10 drops of dilute H2SO4 in the test tube and adds two drops of phenolphthalein solution to it. Then she adds NaOH dropwise. Sara observes a change in colour after adding 20 drops of NaOH. What change in colour would she observe and why?
C. Write a balanced chemical equation for the reaction taking place in the above experiment. Which of the following is true and why? The reaction is a
(a) neutralisation and double displacement reaction
(b) neutralisation and precipitation reaction
(c) precipitation and double displacement reaction
(d) neutralisation, double displacement as well as precipitation reaction.
Q) A hydrocarbon with the formula CxHy undergoes complete combustion as shown in the following equation: 2CxHy + 9O2 → 6CO2 + 6H2O.
(a) What are the values of 'x' and 'y'?
(b) Give the chemical (IUPAC) name of the hydrocarbon.
(c) Draw its electron dot structure.
(d) Name the alcohol which on heating with conc. H2SO4 will produce the above hydrocarbon CxHy.
(e) Write a balanced chemical equation for the reaction of CxHy with hydrogen gas in presence of Nickel.
Section C Physics
Q) A student needs to make a 0.12 Ω resistor. She has some copper wire of 0.80 mm diameter. Resistivity of copper is 1.8 × 10-8 Ωm
(i) Determine the cross-sectional area of the wire.
(ii) Calculate the length of wire required for the 0.12 Ω resistor.
Q) A. (i) Explain why in household circuits only the fuse is connected in series with all the rest of the appliances but all appliances are connected in parallel to each other.
(ii) In a household circuit, an electric heater of power 1500 Wand a fan of power 500 W are connected in parallel to a 220 V supply. A fuse rated for 10 A is connected to the circuit to protect it from excessive current.
(a) Calculate the total current drawn by the heater and the fan.
(b) Determine whether the 10 A fuse is appropriate for this circuit or if it will blow.
OR
B. Two resistors, R1=6 Ω and R2=12 Ω, are connected in parallel to a 24V battery. The circuit operates for 5 minutes.
(i) Calculate the total heat generated in both resistors.
(ii) If each resistor has a power rating of 100 W, determine whether it is safe to use these resistors in the circuit.
