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Science M.C.Q

MODEL PAPER 9 · CBSE STD 10 (CBSE - English Medium). 20 questions.

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M.C.Q

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20 questions · timed · auto-graded

MCQ 11 Mark
Assertion (A): The energy which passes to the herbivores does not come back to autotrophs. .
Reason (R): The flow of energy in a food chain is unidirectional.
  • A
    Both A and R are true and R is the correct explanation of A.
  • B
    Both A and R are true but R is not the correct explanation of A.
  • C
    A is true but R is false.
  • D
    A is false but R is true.
Answer
(a) Both A and R are true and R is the correct explanation of A.
Explanation: The energy flow is unidirectional. The energy that autotrophs absorb from the Sun does not return, and the
energy that goes to herbivores does not go back to the autotrophs. It is no longer accessible to the previous level as it progresses through the various trophic levels.
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MCQ 21 Mark
Assertion (A): A proton moves horizontally towards a vertical long conductor having an upward electric current. It will deflect vertically downward.
Reason (R): Seeing the proton and the conductor from the side of the proton, the magnetic field at the site of the
proton will be towards the right. Hence the force $\vec{F}=q \vec{\nu} \times \vec{B}$ will deflect the proton vertically downward.
  • A
    Both A and R are true and R is the correct explanation of A.
  • B
    Both A and R are true but R is not the correct explanation of A.
  • C
    A is true but R is false
  • D
    A is false but R is true
Answer
(a) Both A and R are true and R is the correct explanation of A
Explanation: Both A and R are true and R is the correct explanation of A
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MCQ 31 Mark
Assertion (A): Sexual reproduction increases genetic diversities and plays a role in origin of new species.
Reason (R): Sexual reproduction involves the formation of gametes and fusion of gametes.
  • A
    Both A and R are true and R is the correct explanation of A.
  • B
    Both A and R are true but R is not the correct explanation of A.
  • C
    A is true but R is false
  • D
    A is false but R is true.
Answer
(a) Both A and R are true and R is the correct explanation of A.
Explanation: Sexual reproduction involves two parents that result in offspring that are not identical to the parents. It causes
variations; which are essential for evolution as well as the survival of species under unfavorable conditions.
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MCQ 41 Mark
Assertion (A): Copper spoon is used to stir silver nitrate solution.
Reason (R): Copper is less reactive than silver
  • A
    Both A and R are true and R is the correct explanation of A.
  • B
    Both A and R are true but R is not the correct explanation of A.
  • C
    A is true but R is false
  • D
    A is false but R is true
Answer
(c) A is true but R is false
Explanation: Silver's reactivity according to the reactivity series is lesser than that of copper (Cu). So, we cannot stir the
solution as the solution would be displaced by copper. We should instead use a glass rod for this. Thus assertion is true, but
reason is false.
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MCQ 51 Mark
Which of the following are environment-friendly practices?
  • A
    Carrying cloth-bag to put purchases in while shopping
  • B
    Walking to school instead of getting your mother to drop you on her scooter
  • C
    Switching off unnecessary lights and fans
  • D
    All of these
Answer
(d) All of these
Explanation:
All the given practices are environment-friendly practices. Carrying cloth-bag for shopping purchases is an alternative to
polythene (which is a non-biodegradable plastic). Switching off lights and fans, when not in use, saves energy and helps to
reduce carbon emissions. Reducing automobile emissions is another way to reduce carbon dioxide emissions.
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MCQ 61 Mark
Depletion of ozone is mainly due to
  • A
    Carbon Dioxide
  • B
    Methane
  • C
    ChloroFloroCarbons
  • D
    Nitrogen
Answer
(c) ChloroFloroCarbons
Explanation: When CFCs reaches upper layers of the atmosphere, they cause depletion of ozone layer, and allow harmful UV
radiations to reach the surface of the earth to create health hazards.
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MCQ 71 Mark
If the potential difference between the end of a wire of fixed resistance is doubled, by how much does the electric power increase?
  • A
    $\frac{4 V}{R}$
  • B
    $\frac{3 V}{R}$
  • C
    $\frac{6 V}{R}$
  • D
    $\frac{5 V}{R}$
Answer
(a) $\frac{4 V}{R}$
Explanation: We know that,
$P =\frac{V 2}{R}$
R is constant
V is doubled
Therefore $P =\frac{2(V 2)}{R}$
$P =\frac{4 V}{R}$
Therefore, when the resistance is doubled, power becomes four times the actual value.
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MCQ 81 Mark
At the time of short circuit, the current in the circuit
  • A
    vary continuously
  • B
    reduced considerably
  • C
    does not change
  • D
    increases heavily
Answer
(d) increases heavily
Explanation: A short circuit is simply a low resistance connection between the two conductors supplying electrical power to
any circuit. This results in excessive current flow in the power source through the 'short,' and may even cause the power
source to be destroyed.
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MCQ 91 Mark
To prepare a temporary mount of leaf peel, one should take
  • A
    All of these
  • B
    freshly plucked leaf
  • C
    leaf placed in sunlight for 48 hours
  • D
    dried and preserved leaf
Answer
(b) freshly plucked leaf
Explanation: A freshly plucked leaf will have living cells and the epidermis will be fully stretched, therefore we can observe
the proper shape of the cells.
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MCQ 101 Mark
Name the chromosomes that possess the gene for maleness and femaleness in humans
  • A
    Sex chromosomes
  • B
    body cell chromosomes
  • C
    Somatic ctromosomes
  • D
    Autosomes
Answer
(a) Sex chromosomes
Explanation: Sex chromosomes possess the gene for maleness and femaleness in humans.
In humans, the sex chromosomes comprise one pair of a total of 23 pairs of chromosomes. The other 22 pairs of chromosomes
are called autosomes.
Individuals having two X chromosomes (XX) are females; individuals having one X chromosome and one Y chromosome
(XY) are males.
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MCQ 111 Mark
Syphilis is caused by
  • A
    Mosquito
  • B
    Virus
  • C
    Parasite
  • D
    Bacteria
Answer
(d) Bacteria
Explanation: Syphilis is a sexually transmitted infection caused by the bacterium Treponema pallidum subspecies pallidum.
The signs and symptoms of syphilis vary depending on which of the four stages it presents (primary, secondary, latent, and
tertiary.
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MCQ 121 Mark
Two pink colored flowers on crossing resulted in 1 red, 2 pink, and 1 white flower progeny. The nature of the cross will be
  • A
    self pollination
  • B
    double fertilisation
  • C
    no fertilisation
  • D
    cross fertilisation
Answer
(a) self pollination
Explanation:
i. Incomplete dominance results in F1 generation plants with all pink flowers when plants with pure red and white blooms
cross.
ii. These plants on self-pollination or fertilization produce progenies (F2 generation) with red, pink, and white flowers in 1:2:1
ratio.
iii. This is a monohybrid cross as only one character or trait is involved in crossing.
iv. The relationship between two genetic variants is referred to as dominant.
v. Each gene has two alleles that an individual inherits from each parent
vi. One allele of a gene, known as the dominant gene, will be expressed if the alleles are different.
vii. The impact of the other allele, known as the recessive one, is concealed.

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MCQ 131 Mark
One of the events that does not occur during photosynthesis is:
  • A
    Chlorophyll absorbs solar energy.
  • B
    Carbon dioxide is released during the process.\
  • C
    Oxygen is released during the process.
  • D
    Carbon dioxide is absorbed during the process.
Answer
(b) Carbon dioxide is released during the process.
Explanation: During this process, the following things take place:
i. Chlorophyll's absorption of light energy
ii. Splitting of water molecules into hydrogen and oxygen and the conversion of light energy into chemical energy.
iii. Carbon dioxide is converted to carbohydrates.
$\underset{\text { carbon dioxide }}{6 CO _2}+\underset{\text { water }}{6 H _2 O } \xrightarrow{\text { photosynthesis }} \underset{\text { glucose }}{ C _6 H _{12} O _6}+\underset{\text { oxygen }}{6 O _2}$
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MCQ 141 Mark
When acetic acid reacts with ethyl alcohol, we add conc. $\ce{H_2SO_4}.$ It acts as $.....$ and the process is called $.....$
  • A
    Reducing agent$,$ Esterification
  • B
    Oxidizing agent$,$ Saponification
  • C
    Acid$,$ Esterification
  • ✓
    Dehydrating agent$,$ Esterification
Answer
Correct option: D.
Dehydrating agent$,$ Esterification
The reaction in which a carboxylic acid combines with an alcohol to form an ester is called esterification. When
acetic acid reacts with ethyl alcohol$,$ an ester is formed along with water. Esterification is a reversible reaction. Concentrated
sulphuric acid acts as a dehydrating agent and absorbs water from the product mix so that the reaction proceeds in the forward
direction.
$\ce{CH_3COOH + C_2H_5OH \stackrel{ H_2SO_4}{\leftrightarrow} CH_3COOC_2H_5 + H_2O}$
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MCQ 151 Mark
A metal X is used in thermite process. When X is burnt in air it gives an amphoteric oxide Y. X and Y are respectively:
  • A
    Fe and $Fe _3 O _4$
  • B
    Al and $Al _3 O _4$
  • C
    Fe and $Fe _2 O _3$
  • D
    Al and $Al _2 O _3$
Answer
(d) Al and $Al _2 O _3$
Explanation: Al and $Al _2 O _3$
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MCQ 161 Mark
A metal is heated with dil $\ce{H_2SO_4}.$The gas evolved is collected by the method shown in the figure. Answer the following questions based on it $:$ Name the gas evolved.
Image
  • ✓
    $H _2$ gas
  • B
    $O _2$ gas
  • C
    $CO$ gas
  • D
    $CO _2$ gas
Answer
Correct option: A.
$H _2$ gas
$H _2$ gas gas is evolved.
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MCQ 171 Mark
While cooking if the bottom of the vessel is getting blackened on the outside, it means that:
  • A
    The fuel is burning completely.
  • B
    The food is not cooked completely.
  • C
    The fuel is not burning completely.
  • D
    The fuel is wet.
Answer
(c) The fuel is not burning completely.
Explanation: When the fuel does not burn completely, some carbon particles remain un-oxidised and form soot. The soot gets
deposited to the bottom of the vessels and the vessels get blackened on the outside.
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MCQ 181 Mark
An acid can react with
  • A
    $PbSO _4$
  • B
    AgCl
  • C
    $Na _2 SO _4$
  • D
    $Na _2 CO _3$
Answer
(d) $Na _2 CO _3$
Explanation: Acids react with metal carbonates to evolve $CO _2$ gas.
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MCQ 191 Mark
Which metal is displaced when zinc metal is put in the solution of copper sulphate?
  • A
    Zinc
  • B
    All of these
  • C
    Copper
  • D
    Sulphate
Answer
(c) Copper
Explanation: Copper
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MCQ 201 Mark
The chips packet is flushed with a gas X to prevent rancidity. Identify X.

Image
  • A
    Oxygen
  • B
    Carbon dioxide
  • C
    Nitrogen
  • D
    Water vapour
Answer
(c) Nitrogen
Explanation: Rancidity can be prevented by packaging fat and oil-containing foods in nitrogen gas as it is unreactive. Hence,
the chips packets are flushed with nitrogen gas to prevent aerial oxidation of fats and oil containing chips.
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