CBSE Class-10 Exam 2016 : Marking Scheme, Science (Foreign)

CBSE Class-10 Exam 2016 : Marking Scheme, Science (Foreign)

CBSE Class-10 Exam 2016 :  Science (Foreign) Set -1

MARKING SCHEME
CLASS X – FOREIGN

Code No. 31/2/1
Expected Answer/ Value point Marks Total
SECTION – A

Q1. Carbon, Due to strong C—C bond ½, ½ 1
Q2. Budding / Regeneration 1/2
Asexual reproduction 1/2 1
Q3. It is the physical, chemical and biological conditions of the region. 1
Q4. Focal length of both the mirrors will be the same / Mirror AB will always form virtual image as it is a diverging / convex mirror ½+ ½ 2
Q5. The development which can be maintained for a long time without undue damage to the environment 1
Two objectives:- i)To provide the economic well being to the present and future
generation , ii)To maintain a healthy environment and life support system ½ + ½ 2
Q6. i)By the local people for the fulfilment of their daily needs ½
ii)By industrialists- deforestation for industrial needs
iii)Deforestation for developmental projects – building,roads, dams etc.
iv)By tourists or in making arrangements for tourists
Q7. Ethanol, C2H5OH /C2H6O ½,1/2
C2H5OH →CH2 = CH2 + H2O
                              Ethene 1, ½
Role of conc H2SO4− dehydrating agent ½ 3
Q8. P—Ethanol, Q—Ethanoic acid ,R—Hydrogen 3x ½
CH 3CH2 OH Acidified K>CH COOH 3
2CH3COOH + 2Na 2 CH3COONa + H2 ½ 3
Q9. i)Aim of classification--systematic study of the known elements
ii)Basic property—Atomic number
iii)Properties of the elements are a periodic function of their atomic numbers.
iv)Metals on the left
v)Non–metals on the right.
vi)Metalloids at the border of metals and beginning of non-metals 6x ½ 3
Q10. X(20)--- 2,8,8,2.It is calcium. ½, ½
Second group,fourth period ½ , ½
CaO + H2O Ca(OH)2 1 3
Q11. Pollination − process of transfer of pollen grains from the anther to stigma of the flower 1
Two types − Self pollination and cross pollination Self pollination is the transfer of pollen grains from anther to stigma of the same flower, whereas in cross pollination transfer of pollen grains is from anther of one flower to the stigma of another flower. ½,1/2
Q12. i)Each piece regenerates into a new planaria 1
ii)Its filaments breaks into smaller pieces/fragments and each fragment gives rise to a new filament.
iii)It releases spores which germinate into new mycelium in moist conditions.

Q13. Two major processes namely formation of gametes and fusion of gametes
constitute sexual reproduction 1
Significance—i) Incorporates the process of combining DNA from two different
individuals during reproduction.
ii) Increases genetic variation.
iii) Promotes diversity in the offsprings.
iv) Plays a role in the origin of new species

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Courtesy: CBSE