SCIENCE (086)
CLASS X
MARKING SCHEME (2022-23)
Q. No Questions Marks
SECTION – A
1. (c) Only iii 1
2. (b) MnO2 is reduced to MnCl2 & HCl is oxidized to Cl2 1
3. (c) Magnesium ribbon burns with brilliant white light 1
4. (b) CO2, Cl2, CO2, CO 1
5. (d) Ferrous sulphate solution remains green with no change in the copper coin. 1
6. (a) Only i 1
7. (c) Addition of hydrogen in presence of catalyst changes A to C 1
8. (b) II,III 1
9. (b) 1
10. (d) 1
11. (d) C only 1
12. (b) B and D 1
13. (c) increases 1
14. (b) 2 (Either North or South) 1
15. (b) diameter d of the wire 1
16. (d) The field consists of concentric circles centred around the wire. 1
17. (c) A is true but R is false 1
18. (a) Both A and R are true and R is the correct explanation of A 1
19. (c) A is true but R is false 1
20. (a) Both A and R are true and R is the correct explanation of A 1
SECTION – B
21. Calcium hydroxide reacts with Carbon dioxide present in the atmosphere to form 2
Calcium carbonate which results in milkiness/white ppt / Formation of Calcium
carbonate (1mark)
Ca(OH)₂ + CO₂ → CaCO₃ + H₂O (1mark)
OR
Fe + HCl → FeCl₂/ FeCl₃ + H₂ (1mark) (No deduction for balancing/ states)
Zn + HCl → ZnCl₂ + H₂ - 1M
, 22. 2
Any four points (½ x4=2 marks)
23. Gallbladder stores bile which helps in emulsification of lipids (1mark). In the 2
absence of stored bile, emulsification of fats will be negligible/ affected/ less
(1mark) and thus fat digestion will be slow. Hence there are such diet restrictions.
24. Glucose, amino acids, salts (any 2, 1 mark each) and a major amount of water are 2
selectively re-absorbed as the urine flows along the tube.
The amount of water reabsorbed depends on how much excess water there is in
the body (0.5 marks), and on how much of dissolved waste there is to be excreted
(0.5marks)
25. Dispersion- The splitting of white light into seven colours on passing through a 2
prism. (1 mark)
Velocity is directly proportional to wavelength given constant frequency. So
yellow will have greater wavelength than blue as the velocity of yellow light is
greater than blue. (0.5 + 0.5 mark)
OR
Angle of deflections of the two prisms need to be equal and opposite. While the
first prism splits the light in the seven colours due to different angles of deflection,
the second prism combines the spectrum along a single ray and the colours again
combine to give white light as the emergent light. (1mark)
(1mark)
26. 2
Excess generation of biodegradable wastes can be harmful as -
Its decomposition is a slow process leading to production of foul smell and gases.
(1mark)
It can be the breeding ground for germs that create unhygienic conditions.(1 mark)
CLASS X
MARKING SCHEME (2022-23)
Q. No Questions Marks
SECTION – A
1. (c) Only iii 1
2. (b) MnO2 is reduced to MnCl2 & HCl is oxidized to Cl2 1
3. (c) Magnesium ribbon burns with brilliant white light 1
4. (b) CO2, Cl2, CO2, CO 1
5. (d) Ferrous sulphate solution remains green with no change in the copper coin. 1
6. (a) Only i 1
7. (c) Addition of hydrogen in presence of catalyst changes A to C 1
8. (b) II,III 1
9. (b) 1
10. (d) 1
11. (d) C only 1
12. (b) B and D 1
13. (c) increases 1
14. (b) 2 (Either North or South) 1
15. (b) diameter d of the wire 1
16. (d) The field consists of concentric circles centred around the wire. 1
17. (c) A is true but R is false 1
18. (a) Both A and R are true and R is the correct explanation of A 1
19. (c) A is true but R is false 1
20. (a) Both A and R are true and R is the correct explanation of A 1
SECTION – B
21. Calcium hydroxide reacts with Carbon dioxide present in the atmosphere to form 2
Calcium carbonate which results in milkiness/white ppt / Formation of Calcium
carbonate (1mark)
Ca(OH)₂ + CO₂ → CaCO₃ + H₂O (1mark)
OR
Fe + HCl → FeCl₂/ FeCl₃ + H₂ (1mark) (No deduction for balancing/ states)
Zn + HCl → ZnCl₂ + H₂ - 1M
, 22. 2
Any four points (½ x4=2 marks)
23. Gallbladder stores bile which helps in emulsification of lipids (1mark). In the 2
absence of stored bile, emulsification of fats will be negligible/ affected/ less
(1mark) and thus fat digestion will be slow. Hence there are such diet restrictions.
24. Glucose, amino acids, salts (any 2, 1 mark each) and a major amount of water are 2
selectively re-absorbed as the urine flows along the tube.
The amount of water reabsorbed depends on how much excess water there is in
the body (0.5 marks), and on how much of dissolved waste there is to be excreted
(0.5marks)
25. Dispersion- The splitting of white light into seven colours on passing through a 2
prism. (1 mark)
Velocity is directly proportional to wavelength given constant frequency. So
yellow will have greater wavelength than blue as the velocity of yellow light is
greater than blue. (0.5 + 0.5 mark)
OR
Angle of deflections of the two prisms need to be equal and opposite. While the
first prism splits the light in the seven colours due to different angles of deflection,
the second prism combines the spectrum along a single ray and the colours again
combine to give white light as the emergent light. (1mark)
(1mark)
26. 2
Excess generation of biodegradable wastes can be harmful as -
Its decomposition is a slow process leading to production of foul smell and gases.
(1mark)
It can be the breeding ground for germs that create unhygienic conditions.(1 mark)
