- CBSE released final date sheet for Class 10 and 12 board exams starting February 17, 2026
- Two board exams will be conducted for Class 10 to allow multiple performance opportunities
- Sample papers provided to help students understand question types and marking schemes
The Central Board of Secondary Education (CBSE) has released the final date sheet for Class 10 and 12 board exams for the academic year 2025-26. The board exams for both the classes will begin on February 17, 2026. Providing students multiple opportunities to improve their performance, the board has decided to conduct two board exams for Class 10 this year.
To help students familiarise themselves with the new examination pattern, CBSE has released sample papers for all subjects. The board has advised students to carefully go through these papers to understand the types of questions, marking schemes, and paper formats.
The following are some of the important questions from the CBSE Board exam sample paper for Chemistry:
Q) Consider the following first order thermal decomposition of SO2Cl2 at a constant volume
SO2Cl2 (g) → SO2(g) + Cl2 (g)
If the total pressure of the gases is found to be 200 torr after 10 seconds and 300 torr upon the complete decomposition of SO2Cl2. Calculate the rate constant.
(Given log 3 = 0.4771, log 2= 0.3010)
II. For a bimolecular elementary reaction A + B → Products. Write the expression for the rate of reaction relating temperature and activation energy for the reaction and also mention what each term represents in the equation.
Q) Answer the following questions:
I. Identify and give any one point of difference between the carbohydrate present in cane sugar and carbohydrate present in milk.
II. Glucose is an aldohexose and a monosaccharide. Which oxidising agent should be used to bring about oxidation of only the aldehydic group present in glucose?
III. Amino acid HOOC-CH2CH(NH2) CH2COOH. Predict whether the pH of this amino acid will be >7, 7 or <7.
IV. Name the two major molecular shapes formed due to the folding of secondary structure of proteins.
V. Ashish's gums bleed frequently. The doctor's prescription mentioned that Ashish is suffering from scurvy. Help him to identify two food sources to help him recover faster.
Q) Attempt either A or B
A. Answer the following questions:
I. Identify and give any one point of difference between the protein present in the hair and protein present in egg albumin.
II. Both glucose and sucrose have aldehydic group, then why does only glucose reduces Fehling's Reagent.and not sucrose?
III. Why do amino acids behave as salts?
IV. What chemical change takes place during curdling of milk?
V. Doctor advised a 50 year old woman enough exposure to sunlight and addition of fish and egg yolk to her diet. What is the possible disease diagnosed by the doctor?
Q) Attempt either A or B
A. Answer the following questions:
I. Write the structure of expected product of Cannizarro reaction of 2-chlorobenzaldehyde.
II. How would the presence of -SO3H group effect the basic strength of aniline.
III. Convert acetic acid to ethanamine.
IV. Write the steps to prepare Benzoic acid from Benzoyl chloride.
V. Give a chemical test to distinguish between: propanal and propanone
Q) Answer the following questions:
I. Write the structure of expected product of Wolf-Kishner reduction of 2 -methylbutanal.
II. How would the presence of -SO3H group effect the acidic strength of benzoic acid
III. Prepare acetic acid from ethanamine.
IV. Convert Aniline to benzoic acid.
V. Give a chemical test to distinguish between: propanal and ethanal.
Iron-EDTA complex in food fortification
Food fortification is defined as the practice of adding vitamins and minerals to commonly consumed foods during processing to increase their nutritional value. It is a proven, safe and cost-effective strategy for improving diets and for the prevention and control of micronutrient deficiencies. A food product (such as rice, wheat flour, edible oil) that is fortified through the addition of fortificants is called a "vehicle".
Reduced iron and several iron salts have been used in the past as iron fortification, however, not all are suitable for this purpose, in terms of iron absorption. Recent studies have shown that beverages containing sugar fortified with either Ferrous sulphate or Fe(III)- EDTA complex have high rate of absorption of iron.
Ferrous sulphate as well as Fe(III)- EDTA is suitable to enrich sugar, but while iron from ferrous sulphate is precipitated and poorly absorbed when fortified sugar is added to beverages such as tea, Fe(III)- EDTA reacts slowly with tea and iron is not precipitated for at least 24 hr.
Fe(III)-EDTA as iron fortification, has demonstrated so far, more advantages than that observed from other iron salts, including ferrous sulphate. But, EDTA is a chelating agent and its use in food technology to prevent oxidative damage of food has been restricted. Excessive consumption of EDTA can cause abdominal cramps, nausea, low blood pressure and damage to kidneys. According to National Institute of Health, it is unsafe to consume more than 3 g of EDTA per day or continuously for more than 5 to 7 days.
The amount of EDTA necessary for 10 mg of iron fortification, is about 60 mg. This is within the safe limits and is comparable to the usual amount added to the diet.
(source: Layrisse, M., & MartInez-Torres, C. (1977). Fe (III)-EDTA complex as iron fortification. The American Journal of Clinical Nutrition, 30(7), 1166-1174.)
Based on the information provided above, answer the following questions:
I. Why is Fe(III)-EDTA complex stable as compared to Ferrous sulphate?
OR
Q) What happens when hard water is titrated against Na2EDTA?
II. You are a doctor, working in Somalia. Will you recommend iron fortified food to your patients? Support your answer with references from the passage.
III. (a)What is the denticity of the ligand in the Fe(III) EDTA complex. Name the atom(s) through which it can bind to the central metal ion.
(b) EDTA is an electron acceptor or an electron donor?
Q) Carry out the following conversions. (Attempt any 3)
I. Butan-2-one to 3-Methylpentan-3-ol
II. Anisole to 4-Methoxytoluene
III. Phenol to Benzene
IV. Chloroethane to Ethoxy ethane
Q) Arrange the products obtained in the following cases in the increasing order of their pKa values:
A. Oxidation of ethanol in presence of acidified potassium dichromate
B. Reaction of propanoic acid with Br2 in the presence of red
Phosphorus
C. Reaction of isopropyl magnesium bromide with carbon dioxide, followed by hydrolysis.
D. Reaction of propanoic acid with Cl2 in the presence of red Phosphorous.
Q)Which of the following elements will:
I. exhibit similar magnetic behaviour and why? Magnesium (Atomic No. 12), Chromium (Atomic No. 24), Iron (Atomic No. 26) and Molybdenum (Atomic No. 42).
II. form white salts and why? Zinc (Atomic No. 30), Scandium (Atomic No. 21), Nickel (Atomic No. 28) and Vanadium (Atomic No. 23)
Q) Explain the following:
I. Toluene on treatment with Cl2 in sunlight gives benzyl chloride whereas when treated with Cl2 in dark gives o-chlorobenzene and p-chlorobenzene.
II. Finkelstein reaction is carried out in the presence of dry acetone.
III. neo pentylchloride has lower boiling point than isopentylchloride.
Q) Write the Nernst equation for the following:
I. Ni (s) + Cu2+ (aq) Ni2+ (aq) + Cu (s)
II. Al (s) + FeSO4 (aq) Al2(SO4)3 (aq) + Fe (s)
III. Mg (s)/Mg2+ (aq)//Ag+ (aq)/Ag(s)
Q) What will be the vapour pressure of a 1 molal aqueous solution of MgCl2, assuming dissociation of MgCl2 to be 70 mole percent? (Vapor pressure of pure water at 25 oC is 23.8 mmHg)
