Q1
mcq
1 mark
Select from the following decomposition reactions in which the source of energy for decomposition is heat:
- A. (i) and (ii)
- B. (ii) and (iii)
- C. (iii) and (iv)
- D. (i) and (iv)
Correct Answer: C —
Solution
Decomposition reactions in which heat is the source of energy are called thermal decomposition reactions. In such reactions, a compound breaks down on heating. Therefore, the correct option is (iii) and (iv), where decomposition occurs due to heat. The other reactions are caused by some other form of energy, not heat.
Q2
mcq
1 mark
The number of covalent bond(s) present in a nitrogen molecule is/are: (Atomic number of nitrogen is 7)
- A. 1
- B. 3
- C. 5
- D. 7
Correct Answer: B —
Solution
A nitrogen molecule is $N_2$. Each nitrogen atom has 5 valence electrons and needs 3 more electrons to complete its octet. So the two nitrogen atoms share three pairs of electrons, forming a triple covalent bond. Hence, the number of covalent bonds present is 3. Therefore, option (b) is correct.
Q3
mcq
1 mark
Consider the reactions of dil. hydrochloric acid with the following metals: Aluminium, Copper, Iron, Magnesium and Zinc. The correct observation is:
- A. Most vigorous reaction with aluminium and no reaction with iron
- B. Most vigorous reaction with magnesium and no reaction with iron
- C. Most vigorous reaction with magnesium and no reaction with copper
- D. Most vigorous reaction with zinc and no reaction with copper
Correct Answer: C —
Solution
Among the given metals, magnesium is the most reactive and therefore reacts most vigorously with dilute hydrochloric acid. Copper is below hydrogen in the reactivity series, so it does not react with dilute HCl. Iron, zinc and aluminium do react, but less vigorously than magnesium. Hence, the correct observation is: most vigorous reaction with magnesium and no reaction with copper. So, option (c) is correct.
Q4
mcq
1 mark
From the following, select a process in which combination reaction occurs:
- A. Black and white photography
- B. Burning of carbon (coal)
- C. Burning of methane
- D. Refining of copper
Correct Answer: B —
Solution
A combination reaction is one in which two or more substances combine to form a single product. Burning of carbon is a combination reaction because carbon combines with oxygen to form carbon dioxide: $C + O_2 \rightarrow CO_2$. Black and white photography, burning of methane, and refining of copper are not combination reactions in this sense. Hence, option (b) is correct.
Q5
mcq
1 mark
Oxides of aluminium and zinc are:
- A. Acidic
- B. Amphoteric
- C. Basic
- D. Neutral
Correct Answer: B —
Solution
Oxides of aluminium and zinc are amphoteric oxides. This means they react with both acids and bases to form salt and water. Therefore, option (b) is correct.
Q6
mcq
1 mark
Application of Abscisic acid on plants promotes:
- A. Development of fruits
- B. Wilting of leaves
- C. Elongation of stem
- D. Formation of flowers
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Q7
mcq
1 mark
The valves in the human heart ensure that: (i) Oxygen-rich blood flows from left atrium to left ventricle only. (ii) Deoxygenated blood flows from left atrium to left ventricle only. (iii) Oxygen-rich blood flows from right atrium to right ventricle only. (iv) Deoxygenated blood flows from right atrium to right ventricle only.
- A. $(i)$ and $(iii)$
- B. $(ii)$ and $(iv)$
- C. $(i)$ and $(iv)$
- D. $(ii)$ and $(iii)$
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Q7
mcq
The valves in the human heart ensure that:
- A. (i) and (iii)
- B. (ii) and (iv)
- C. (i) and (iv)
- D. (ii) and (iii)
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Q8
mcq
1 mark
The part of the hindbrain present immediately above the medulla is:
- A. Cerebellum
- B. Pons
- C. Cerebrum
- D. Spinal cord
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Q9
mcq
1 mark
In garden pea, violet colour flower is the dominant trait over white colour flower which is the recessive trait. When parent plant with violet coloured flowers $(Vv)$ is crossed with a parent plant with white flowers, the possible percentage of occurrence of traits in the F1 progeny would be:
- A. 100% violet
- B. 50% violet, 50% white
- C. 25% violet, 75% white
- D. 75% violet, 25% white
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Q10
mcq
1 mark
The end product of meiosis in a reproductive cell in plants is:
- A. Zygote
- B. Pollen grains
- C. Sperms
- D. Egg
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Q11
mcq
The organism occupying the fourth trophic level in a food chain operating in grassland is:
- A. Green plants
- B. Frog
- C. Grasshopper
- D. Snake
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Q12
mcq
The strength of the magnetic field inside a current carrying long straight solenoid is:
- A. maximum at its centre.
- B. minimum at its centre.
- C. maximum at the ends and minimum at its centre.
- D. uniform throughout its length.
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Q13
mcq
An optical device which always produces images of $m = +1$ is:
- A. Plane mirror
- B. Convex mirror
- C. Concave mirror
- D. Convex lens
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Q14
mcq
Which one of the following factors affects the electrical resistivity of a conductor?
- A. Temperature
- B. Length
- C. Shape
- D. Thickness
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Q15
mcq
Concave mirror finds its application in which of the following cases?
- A. A solar furnace
- B. A rear-view mirror in vehicles
- C. To view full size erect image of distant tall buildings
- D. To produce divergent beam of light
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Q16
mcq
In an ecosystem, 10% of energy available for transfer from one trophic level to the next in a food chain is in the form of:
- A. heat energy
- B. chemical energy
- C. mechanical energy
- D. light energy
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Q17
mcq
Assertion (A): In our homes we receive supply of electric power through a main supply. One of the wires in this supply, usually with red insulation, is called live wire and another wire with green insulation is called neutral wire.
Reason (R): In our country, the potential difference between the live wire and the neutral wire is 220 volts.
- A. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- B. Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
- C. Assertion (A) is true, but Reason (R) is false.
- D. Assertion (A) is false, but Reason (R) is true.
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Q18
mcq
Assertion (A): Decomposition of vegetable matter into compost is an exothermic reaction.
Reason (R): Decomposition reactions need energy to break down the reactants.
- A. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- B. Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
- C. Assertion (A) is true, but Reason (R) is false.
- D. Assertion (A) is false, but Reason (R) is true.
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Q19
mcq
Assertion (A): Due to scattering of sunlight, the clear sky predominantly appears blue.
Reason (R): The wavelength of blue light is nearly 1.8 times the wavelength of red light.
- A. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- B. Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
- C. Assertion (A) is true, but Reason (R) is false.
- D. Assertion (A) is false, but Reason (R) is true.
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Q20
mcq
Assertion (A): Transpirational pull helps in the absorption and upward movement of water and dissolved minerals in plants.
Reason (R): The effect of root pressure in transport of water is more significant at night.
- A. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- B. Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
- C. Assertion (A) is true, but Reason (R) is false.
- D. Assertion (A) is false, but Reason (R) is true.
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Q21
short answer
2 marks
Draw a ray diagram to show the path of a ray of light which falls obliquely on one of the faces of an equilateral triangular prism made of glass and mark on it the angle of incidence ($\angle i$) and the angle of deviation ($\angle D$).
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Q22
short answer
2 marks
Translate the following statements into balanced chemical equations:
(a) Aluminium reacts with copper chloride to form aluminium chloride and copper.
(b) Zinc reacts with sodium hydroxide to give sodium zincate and hydrogen gas.
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Q23
short answer
2 marks
(a) (i) What is an alloy?
(ii) Write the composition of solder and the property which makes it suitable for welding electric wires.
OR
(b) During electrolytic refining of silver:
(i) What are the electrodes – cathode and anode made up of?
(ii) What is anode mud? Why is it called so?
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Q24
short answer
2 marks
Explain how circulation of blood takes place in fishes.
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Q25
short answer
2 marks
An object is placed 18 cm in front of a concave mirror of focal length 12 cm. Use mirror formula to determine the position of the image formed in this case.
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Q26
short answer
2 marks
(a) Explain how tendrils help a pea plant climb up other plants or fences.
OR
(b) List two major limitations of the use of electrical impulses as a means of communication between the cells in most multicellular animals.
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Q33
long answer
As shown in the figure a small aluminum rod AB is suspended horizontally between the poles of a strong horseshoe magnet. This rod is also connected with a battery and a key. Study the arrangement shown.
(a) State Fleming’s left-hand rule.
(b) Apply Fleming’s left-hand rule to determine :
(i) What is observed when a current is passed from B to A in the rod ?
(ii) What is observed when a current is passed from A to B in the rod ?
(iii) What is observed when the rod AB is aligned parallel to the magnetic field and current is passed through it from B to A ? Justify your answer in this case.
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Q34
long answer
(a) (i) Differentiate between self-pollination and cross-pollination.
(ii) Explain the events taking place in a flower after a pollen lands on a suitable stigma, till fruit-formation.
OR
(b) (i) What is the site of fertilisation of egg in a female reproductive tract ?
(ii) Fertilised egg on implantation in uterus lining continues to grow and develop to become a foetus. Explain how it gets nourishment and removes metabolic wastes during this period.
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Q35
long answer
(a) (i) Define the term power of accommodation of human eye. What happens to the image distance in the eyes when the distance of an object is increased gradually from about 5 m to 500 m from our eyes ? Name and explain the role of the part of human eye responsible for it in this case.
(ii) A person is unable to see distinctly the objects placed beyond 2 m from his eyes. Name the defect of vision the person is suffering from. List two possible causes of this defect and write the type of lenses used for the correction of this defect.
OR
(b) (i) Name and explain the phenomenon of light responsible to make the path of a beam of light visible when it enters a smoke/dust-filled room through a small hole. Also state the dependence of the colour of the light we receive on the size of the particles of the medium through which the light passes.
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Q35
short answer
(ii) A person is suffering from a defect of vision and uses spectacles with lens powers of +2.0 D and −0.5 D. Which lens is used for seeing distant objects clearly and what is its focal length ?
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Q35
long answer
3 marks
A person is unable to see distinctly the objects placed beyond 2 m from his eyes. Name the defect of vision the person is suffering from. List two possible causes of this defect and write the type of lenses used for the correction of this defect.
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Q35
long answer
2 marks
(b) (i) Name and explain the phenomenon of light responsible to make the path of a beam of light visible when it enters a smoke/dust-filled room through a small hole. Also state the dependence of the colour of the light we receive on the size of the particles of the medium through which the light passes.
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Q36
long answer
(a) (i) State the relation between hydrogen ion concentration and its pH.
(ii) Why is the process of dilution carried out when a concentrated acid is mixed with water?
(iii) Why do hydrochloric acid and acetic acid of the same concentration, in equal volumes, produce different amounts of hydrogen ions?
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Q36
long answer
2 marks
(ii) A person suffering from presbyopia needs spectacles having bifocal lenses. If the power of two lenses used in his spectacles is +2.0 D and −0.5 D, which one of the two lenses is for the correction of his distant vision and what is its focal length ?
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Q36
long answer
5 marks
(a) (i) Give the relation between hydrogen ion concentration of an aqueous solution and its pH.
(ii) Concentrated acids should not be diluted by adding water to acid. Why ?
(iii) Why do same molar concentrations of hydrochloric acid and acetic acid not produce same amounts of hydrogen ions ?
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Q36
long answer
5 marks
(b) Give reason : 5×1=5
(i) Crystals of washing soda change to white powder on exposure to air.
(ii) Plaster of Paris should be stored in moisture-proof containers.
(iii) Baking soda can be used on bee sting area to get relief.
(iv) Distilled water does not conduct electricity.
(v) Farmers treat the soil of their fields with quick lime.
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Q37
long answer
2 marks
The process of determining the sex of a newborn is purely genetic. But still many people in some societies believe that only the woman (mother) is responsible for determination of the sex of the child and blame her. In fact, the sex of the child is genetically determined. But there are some animals where sex is not genetically determined.
(a) Define sex chromosomes. 1
(b) Mention one example of animals where sex is not genetically determined. How is sex determined in these animals ? Explain. 1
(c) (i) Does the genetic combination of the mother play a significant role in determining the sex of newborn ? Explain. 2
OR
(c) (ii) How is equal genetic contribution of male and female parents ensured in progeny ? 2
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Q37
short answer
(a) Define sex chromosomes.
(b) Mention one example of animals where sex is not genetically determined. How is sex determined in these animals? Explain.
(c) (i) Does the genetic combination of the mother play a significant role in determining the sex of newborn? Explain.
OR
(c) (ii) How is equal genetic contribution of male and female parents ensured in progeny?
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Q38
short answer
In a domestic circuit, six LED bulbs and a ceiling fan are arranged as per the circuit shown in the figure. The source voltage is 220 volts and the power rating of each device is marked in the circuit diagram. Two fuses $F_1$ and $F_2$ are also provided in the circuit. Based on the circuit diagram, answer the following questions:
(a) State what happens when (i) only key $K_1$ is closed, (ii) key $K_2$ is also closed.
(b) Find the current drawn by the bulb $L$.
(c) (i) Calculate the resistance of the bulb $A$. Find the total resistance offered by the circuit to the flow of current when only key $K_2$ is closed.
OR
(c) (ii) What would happen to the glow of the bulbs in the circuit when $K_1$ and $K_2$ both are closed and the fuse $F_1$ melts suddenly? Give reason to justify your answer.
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Q39
short answer
All compounds of carbon which contain only carbon and hydrogen are called hydrocarbons. Among these, saturated hydrocarbons are called ‘alkanes’, unsaturated compounds with one or more double bonds are called ‘alkenes’ and compounds containing one or more triple bonds are called ‘alkynes’.
(a) Identify the following compound and write its name.
$\mathrm{CH_3 - C \equiv CH}$
(b) How do saturated and unsaturated carbon compounds differ in terms of the flame produced by them on burning?
(c) (i) Which type of hydrocarbons undergo addition reactions? Show with an example.
OR
(c) (ii) What are structural isomers? Draw two structural isomers of butane ($\mathrm{C_4H_{10}}$).
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