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SBM 4201 SCIENCE TEST PAPER I QUESTIONS WITH ANSWERS 2022/2023 A+SUCCESS GUARANTEED
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SBM 4201 SCIENCE TEST PAPER I QUESTIONS WITHANSWERS 2022/2023 A+SUCCESS GUARANTEED
SECTION – A
1. Explain why carbon forms compounds mainly by covalent bonds?
Ans: Carbon is a tetravalent element and hence forms covalent compounds. Carbon doesn't
prefer losing or gaining electrons due to the effective nuclear charge. It prefers sharing electrons
to get the stable electronic configuration and hence forms only covalent bonds.
OR
Briefly explain two main reasons why carbon forms such a large number of compounds.
Ans: The two main reasons for the formation of a large number of compounds by carbon are: (i)
Catenation: Carbon atom has the ability to form bonds with other atoms of carbon leading to long
chains of carbon compounds. (ii) Tetravalency: Having a valency of four or being tetravalent,
carbon is capable of bonding with four other atoms of carbon or other elements.
2. Define pollination.
Ans: The transfer of pollen grains from the anther of a stamen to the stigma of a carpel is called
pollination.
OR
What do you mean by cross pollination?
Ans: When pollen grains from anther of a flower on one plant are transferred to the stigma of a
flower on another similar plant is called cross-pollination.
3. A teacher provided acetic acid, water, lemon juice, aqueous solution of sodium hydrogen
carbonate and sodium hydroxide to students in the school laboratory to determine the pH values
of these substances using pH papers. One of the students reported the pH values of the given
substances as 3, 12, 4, Band 14 respectively. Which one of these values is not correct? Write its
correct value stating the reason.
Ans: The value of pH for water is not correct. The correct value of pH of water is 7 because it
has almost equal concentration of H+ and OH– due to which it is neutral.
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,SBM 4201 SCIENCE TEST PAPER I QUESTIONS WITH
ANSWERS 2022/2023 A+SUCCESS GUARANTEED
4. What is baking soda used for?
Ans: Baking soda is used in the kitchen for faster cooking and for raising the dough in batter. It
is also used to make crisp pakoras and chips Baking soda has several other uses which are as
follows:
(i) It is used in antacids as its mild basic nature helps to neutralise acidity in the stomach.
(ii) The carbon dioxide releases on heating causes bread or cake to raise, making them spongy.
(iii) It is also used in soda acid fire extinguisher.
5. Which of these statements is incorrect? Give reasons.
(a) Sugarcane juice and water are mixed and heated to form sweet liquid called molasses.
(b) Breakdown of complex substances into simpler substances by anaerobic bacteria is called
fermentation.
(c) Glucose and fructose are the final products of fermentation.
(d) Zymase converts glucose and fructose into ethanol and carbon dioxide.
Ans: In fermentation, glucose and fructose formed by molasses is further converted into ethanol
and carbon dioxide. Hence, the incorrect option is (c).
6. A, B and C are three elements which undergo chemical changes according to following equations:
a. A2O3 + 2B → B2O3 + 2A
b. 3CSO4 + 2B → B2(SO4)3 + 3C
c. 3CO + 2A → A2O3 + 3C
Which of these metals is most reactive? Give reason to support your answer.
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,SBM 4201 SCIENCE TEST PAPER I QUESTIONS WITH
ANSWERS 2022/2023 A+SUCCESS GUARANTEED
(a) A (b) B (b) C (d) All of these
Ans: B is most reactive as it displaces both A and C from their solution.
7. Why do cricketers complain of cramps in their muscles during playing?
Ans: During playing there is conversion of pyruvate to lactic acid in muscles under anaerobic
conditions which leads to formation of cramps in their muscles.
OR
Where does the digestion of fat take place in our body?
Ans: In the human body fat is digested in the small intestine. Fats are present in the form of large
globules which are difficult for enzymes to digest.
8. Why do acids not show acidic behaviour in the absence of water?
Ans: Acids do not show acidic behaviour in the absence of water because the dissociation of
hydrogen ions from an acid occurs in the presence of water only. It is the hydrogen ions that are
responsible for the acidic behaviour.
9. Show electron dot structure for the transfer of electrons between the atoms during the formation
of magnesium oxide.
Ans:
OR
Why ionic compounds do not conduct electricity in their solid state but conduct electricity in
their molten or aqueous solution state?
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, SBM 4201 SCIENCE TEST PAPER I QUESTIONS WITH
ANSWERS 2022/2023 A+SUCCESS GUARANTEED
Ans: In solid state the ions present in the ionic compounds are held by strong electrostatic force
of attraction so the ions are not free to conduct electricity. But in molten or aqueous solution
state the ions are free to move so they can conduct electricity.
10. What is the role of decomposers in the ecosystem?
Ans: Decomposers act upon dead and decay organisms to convert them into simpler forms.
These simple substances get mixed up in the soil and are used as nutrients by the producers.
From producers it goes to consumers and so on. They maintain the balance in the ecosystem and
provide space for new life in ecosystem.
OR
What will happen if we kill all the organisms in one trophic level?
Ans: If we will kill all the organisms in one trophic level the transfer of food energy to the next
trophic level will stop i.e., the organisms which are placed higher than this trophic level will die
due to lack of food. Similarly the trophic level lower than this one will increase their number.
Thus an imbalance would be created in the ecosystem.
11. Give reasons why acquired characters are not inherited?
Ans: Acquired characters are developed by an individual during its life time. They are not
present in the DNA of germ cells. They only involve changes in the non-reproductive tissues and
hence these characters are not inherited.
12. How does Planaria reproduce? Is this method sexual or asexual?
Ans: Planaria reproduces by the process of regeneration. It is a type of asexual reproduction in
which Planaria is cut into any number of pieces and each piece grows into a new organism.
13. What is an ecosystem?
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