Science Olympiad Model Test Paper - 1 | Olympiad Preparation for Class 10 PDF Download

Ans: (c)

• To find the smallest number after swapping the first and last digits, we first need to perform the interchange on each number.
• After swapping, we arrange the new numbers in ascending order.
• The unit digit of the smallest number in this new arrangement will be our answer.
• Upon performing these steps, we find that the unit digit of the smallest number is 4.

Ans: (a)

• To solve this, we first note that T is on the left end, meaning T is in position 1.
• Since R is in the second position from the right, it must be in position 4, leaving position 5 for S.
• With P next to Q and to the right of both Q and T, Q must be in position 2 and P in position 3.
• This arrangement shows that P is indeed sitting between Q and R.

Ans: (c)

• The expression ‘P + Q % R $ S + T & W’ can be broken down as follows:
• P is the son of Q.
• Q is the mother of R.
• R is the daughter of S.
• S is the mother of T.
• T is the husband of W.
• From this, we can conclude that R is indeed the granddaughter of W.

Ans: (c)

Each time the gap between the numbers is decreasing by 3.

99 – 102 = -3

93 – 99 = -6

84 – 93 = -9

72 – 84 = -12

To find the next term in the series, we need to do:

72 – 15 = 57

Ans: (a)

• To find the pairs of letters in the word RESOURCES, we need to check the distance between each letter and see if it matches their position in the English alphabet.
• For example, the letters R and T are 1 letter apart in the alphabet, and they are also 1 letter apart in the word.
• After checking all combinations, we find that there are 2 pairs that meet this criterion.
• Thus, the answer is 2.

Ans: (b)

The series is going up in cubes of continuous numbers, starting with the cube of 3.

10 + 3³ = 37

37 + 4³ = 101

101 + 5³ = 226

226 + 6³ = 442

Ans: (a)

According to the question,

S → 09

C → 11

R → 17

I → 23

B → 06

B → 06

L → 18

E → 24

If we re-arrange SCRIBBLE, LIBBERS will be formed.

L→ 18

I → 23

B → 06

B → 06

E → 24

R → 17

S → 09

So, LIBBERS is coded 18-23-06-06-24-17-09.

Ans: (c)

EMPTY is coded as FOSXD using the pattern:-

E + 1 = F

M + 2 = O

P + 3 = S

T + 4 = X

Y + 5 = D

In the same way, STRING will be coded as TVUMSM:-

S + 1 = T

T + 2 = V

R + 3 = U

I + 4 = M

N + 5 = S

G + 6 = M

Ans: (c)

Grandfather's wife → Meera's grandmother

Son of grandmother → Meera's father

Daughter of Meera's father → Meera's sister

Ans: (d)

S = Start point and E = End point.

Ans: (a)

• The apparent loss in weight of the body is calculated by subtracting the weight in water from the weight in air: 500 gf - 300 gf = 200 gf.
• This loss in weight is equal to the upthrust (or buoyant force) acting on the body, which is also 200 gf.
• To find the volume of the body, we use the relationship that 1 gf of weight corresponds to 1 cm³ of water displaced. Thus, the volume is 200 cm³.
• Therefore, the answers for the apparent loss in weight, upthrust, and volume are 200 gf, 200 gf, and 200 cm³, respectively.

Ans: (b)

• We can find the direction of the magnetic field by using the right thumb hand rule which states that if the thumb gives the direction of the current, then the direction of the magnetic field lines can be determined by the curling of the fingers.
• Here, the magnetic field at point P due to AB and CD segments will cancel each other and the magnetic field due to the semicircular section will be directed upwards (outward to the plane of paper).

Ans: (c)

• Statement (i) is false because magnetic field lines do not travel parallel; they spread out from the North to South pole and cannot intersect.
• Statement (ii) is false as a straight copper conductor does not become permanently magnetized when current flows through it.
• Statement (iii) is true since the strength of the magnetic field at the center of a circular coil does decrease as the radius increases.

Ans: (c)

• Fe(s) + CuSO₄(aq)  FeSO₄(aq) + Cu(s)
• The given reaction is a displacement reaction as well as a redox reaction.
• The Cu⁺² ion in CuSO₄ is reduced to Cu. Hence, CuSO₄ is acting as an oxidising agent.
• Fe is getting oxidised to Fe⁺² in FeSO₄. Hence, Fe is acting as a reducing agent.
• Therefore, statements II and IV are incorrect.

Ans: (b)

Safe current through the fuse wire is independent of the length of the wire. It depends upon the radius of the fuse wire as I² ∞r³.

Ans: (c)

The bases which dissociate in aqueous solution to produce one mole of hydroxyl ion per mole of the base are called monoacidic bases.

For example, NaOH, KOH and NH₄OH

NaOH ⇔ Na⁺+ OH^-

Ammonium hydroxide is a monoacidic base and can exist as either NH₃ and H₂O or NH₄⁺ and OH^- through a reversible reaction.

When ammonium hydroxide is allowed to reach equilibrium, far more NH₃ and H₂O exist compared to NH₄⁺ and OH^-, so the concentration of OH^- is low; hence, ammonium hydroxide is considered to be a weak alkali.

Ans: (c)

As the resistance of the wire is directly proportional to the length of the wire, the resistance of the larger length is 6Ω and the resistance of the smaller length is 2Ω.

P = V2 / R = 12 x 12 / 6
P = 24 W

Ans: (a)

The correct statements are as follows:

I. Metals have 1 to 3 electrons in their valence shell and non-metals have 4-8 electrons in their valence shell.

II. Metallic oxides form bases on reaction with water and non-metallic oxides form acids on reaction with water.

III. Among the metals, the more electropositive metals displace the less electropositive metals from their salt solutions.

IV. Non-metals accept electrons to attain a stable configuration and form anions.

V. Metals like Au and Pt are less reactive and do not form oxides.
Hence, option (a) is correct.

Ans: (c)

Order of bond strength of carbon-carbon bonds:

C₂H₂ is ethyne and has the structure  .

Hence, the carbon-carbon bond is the strongest in ethyne.

Ans: (c)

Non-commercial energy sources include fuel wood, straw and dried dung. These are commonly used in rural India. According to an estimate, the total availability of fuel wood in India was only 50 million tonnes a year. It is less than 50% of the total requirement. In coming years, there would be a shortage of firewood.

Ans: (c)
Metals + H₂O(l)  Metal hydroxide + H₂
Metals + H₂O(g)  Metal oxide + H₂
Since calcium metal can react with water, it will yield a hydroxide.

All the other observations are correct.

Ans: (b)

• The time between claps: The frequency of 12 Hz means she claps every 1/12 seconds, which is 0.0833 s, not 0.2 s. So, statement (i) is incorrect.
• Distance calculation: The time for the echo to return after one clap is 0.2 s (0.1 s to the wall and 0.1 s back). The distance is calculated as speed × time = 330 m/s × 0.1 s = 33 m. Thus, statement (ii) is correct.
• Four echoes: If she hears four more echoes, it means 4 × 0.2 s = 0.8 s. The distance is 330 m/s × 0.4 s = 132 m, so statement (iii) is incorrect.

Ans: (c)

• The pH scale measures how acidic or basic a solution is. A pH of 2.2 – 2.4 indicates a very acidic solution, which corresponds to lemon juice.
• A pH of 6.8 is slightly acidic and can be associated with milk.
• A pH of 7.4 is neutral and is typical for human blood.
• A pH of 10 indicates a basic solution, which is consistent with milk of magnesia.

Ans: (a)

• Components of inkchromatography, which is a method to separate mixtures.
• Petrol and waterseparating funnel.
• Salt and ammonium chloridesublimation, where one component turns into gas.
• Separation of components of airfractional distillation, which separates based on boiling points.

Ans: (c)

• X is a substance commonly found in antacids, which help neutralize stomach acid.
• It is also used in soda-acid fire extinguishers, making it important for safety.
• Options (a) and (b) are incorrect because they misrepresent the properties of X.
• Option (d) incorrectly identifies Y; it is not carbon dioxide but rather a different product of the reaction.

Ans: (b)

In precipitation reactions, when a product formed by the displacement of anion or cation in the solution surpasses its point of saturation, then it precipitates as solid at the bottom of the solution.

For example, 2KI + PbSO₄ → PbI2 + K₂SO₄

Here, lead and potassium are displaced from their compounds to form lead iodide that precipitates at the bottom of the container.

Ans: (d)

• To find the mole ratio, we need to calculate the number of moles for each element using the formula: moles = mass (g) / molar mass (g/mol).
• For calcium (Ca), the molar mass is about 40 g/mol, so 10 g of calcium is 0.25 moles.
• For magnesium (Mg), the molar mass is about 24 g/mol, so 18 g of magnesium is 0.75 moles.
• The ratio of moles of calcium to magnesium is 0.25:0.75, which simplifies to 1:3, confirming that option (d) is correct.

Ans: (c)

• The compound CH₃CH₂ – COOCH₃ is actually an ester, not an acid. The correct IUPAC name for this compound is ethyl acetate.
• Butanone (option a) is correctly named as it has a ketone functional group.
• Propanal (option b) is the correct name for the aldehyde with the structure CH₃CH₂ – CHO.
• Butanol (option d) is accurately named for the alcohol with the structure CH₃– CH₂ – CH₂ – CH₂ – OH.

Ans: (a)

• The question asks to identify the incorrect matches among the given reactions.
• Burning of natural gas is indeed an exothermic reaction, which releases heat.
• The decomposition of vegetable matter into compost is incorrectly labeled as endothermic; it is actually an exothermic process.
• The reaction of zinc with copper sulfate is a single displacement reaction, not a decomposition reaction.
• The reaction of barium chloride with sodium sulfate is a double displacement reaction, not a single displacement reaction.

Ans: (c)

• The compound X with the formula C₂H₄O₂ is acetic acid (CH₃COOH).
• When X reacts with C₂H₅OH (ethanol), it forms ethyl acetate (CH₃COOCH₂CH₃), which is Y.
• When X reacts with sodium carbonate, it produces a salt, water, and carbon dioxide (CO₂), which is the gas Z that causes effervescence.
• Thus, X, Y, and Z are acetic acid, ethyl acetate, and carbon dioxide, respectively.

Ans: (b)

• Statement I is correct; silver and copper are indeed excellent conductors of heat.
• Statement II is incorrect; alkali metals like lithium and sodium actually have low densities and low melting points.
• Statement III is incorrect; metals typically form basic oxides, while non-metals form acidic oxides.
• Statement IV is incorrect; metals like aluminum, iron, and zinc do not react with cold water.

In summary, the incorrect statements are II, III, and IV, making option (b) the correct choice.

Ans: (a)

C, N and O are elements of the second period.

The atomic radius decreases across the period because the effective nuclear charge increases across the period.

Hence, the correct order of the atomic radii is:

C > N > O

Ans: (b)

•  The atomic numbers of C and D are in a ratio of 1:2, which means if C has an atomic number of 12, D must have 24. This makes statement I true.
• However, the number of valence electrons in C and D is not correctly stated in II, as C should have 4 and D should have 8, making II false.
• Statement III is true because if we assume C has 12 protons, it has 12 neutrons (for a stable isotope), and D has 24 protons, likely having 21 neutrons, leading to a difference of 3 neutrons.
• Statement IV is false because the valency of C and D is not 2; C has a valency of 4 and D has a valency of 2.

Ans: (c)

• To form an ion with two positive charges, an element must lose two electrons.
• Element P has the configuration (2, 8, 2) and can lose 2 electrons from its outer shell.
• Element Q has the configuration (2, 8, 8, 2) and can also lose 2 electrons from its outer shell.
• Elements R and S cannot lose 2 electrons to form a +2 ion.
• Thus, the correct answer is P and Q, which can both form a +2 ion.

Ans: (d)

• Chlorophyll captures light energy during photosynthesis.
• This energy is crucial for multiple processes, including the formation of ATP, which provides energy for the plant.
• It also aids in the synthesis of NADPH, a molecule that carries electrons for chemical reactions.
• Additionally, chlorophyll facilitates the photolysis of water, which splits water molecules to release oxygen.
• Therefore, the correct answer is all of these functions are carried out by the energy absorbed by chlorophyll.

Ans: (a)

• The tall pea plant has the genotype TTyy, meaning it has two dominant alleles for height (T) and two recessive alleles for seed color (y).
• The dwarf pea plant has the genotype ttYY, which means it has two recessive alleles for height (t) and two dominant alleles for seed color (Y).
• When these plants are crossed, all offspring will inherit one allele from each parent, resulting in the genotype TtYy.
• This genotype expresses the tall phenotype due to the presence of the dominant T allele and the yellow seed color due to the dominant Y allele.

Ans: (b)

• Denatured alcohol is ethanol made unfit for human consumption by adding one or more chemicals (denaturants) to it. The additive may be any of the substances like methanol, copper sulphate, pyridine, etc.
• This practice is carried out to prevent the misuse of ethanol as an industrial raw material.
• Since the additives are added in a small quantity, option (2) is correct.

Ans: (b)

Limewater is a saturated solution of calcium hydroxide which is used as a whitewash.

Atmospheric CO2 reacts with limewater to form calcium carbonate, which gives it a brilliant sheen.

Ans: (c)

S(s) + O₂(g) →  SO₂(g)

This is a combination reaction as two reactants combine to give one product.

It is a redox reaction as sulphur is getting oxidised and oxygen is getting reduced.

Ans: (d)

Organic acids are carboxylic acids, having an carboxyl group –COOH.

Lactic acid is an example of an organic acid.

Ans: (c)

• The growth of cartilage occurs in a unidirectional manner, meaning it grows in one direction.
• Cartilage is found in the pinna of the ears, which is the outer part of the ear.
• Understanding these points helps clarify the nature of cartilage growth and its locations in the body.
• Other options mention incorrect locations or growth patterns for cartilage.

Ans: (a)

• Water stored underground plays a crucial role in recharging wells, which is essential for local water supply.
• It is beneficial as it does not promote mosquito breeding, helping to reduce health risks.
• This stored water is also utilized for the benefit of the local population, supporting agriculture and daily needs.
• Thus, all three statements (i), (ii), and (iii) are true regarding the advantages of underground water storage.

Ans: (b)

• The question asks for the incorrect match among the options provided.
• Rhizobium is correctly known for converting atmospheric nitrogen into usable forms for plants.
• Nitrobacter accurately converts nitrites into nitrates, which is essential for plant nutrition.
• Putrefying bacteria play a role in breaking down nitrogen-containing proteins into ammonia.
• However, Azotobacter does not convert ammonia into nitrites; it actually fixes atmospheric nitrogen into ammonia, making option (b) the incorrect match.

Ans: (d)

• Houseflies are known to carry and spread various diseases.
• Among the listed diseases, Typhoid, Dysentery, Cholera, and Tuberculosis can all be transmitted by houseflies.
• Houseflies can contaminate food and water, leading to the spread of these diseases.
• Therefore, the correct answer includes all the diseases listed: (i), (ii), (iii), and (iv).

Ans: (c)

Vitamin C is also known as ascorbic acid or L-ascorbic acid.

It is a vitamin found in fresh fruits and vegetables, particularly citrus fruits and also taken as a dietary supplement.

Ans: (d)

Sulphuric acid gives sodium sulphate, carbon dioxide gas and water when it reacts with sodium carbonate.

Ans: (a)

• Follicle-stimulating hormone (FSH) is responsible for the development of the primary follicle into the Graafian follicle.
• The luteinizing hormone (LH) triggers the corpus luteum to produce progesterone, which is crucial for maintaining pregnancy.
• Ovulation is primarily regulated by the rise in luteinizing hormone levels in the bloodstream.
• Thus, the correct sequence of hormones is FSH, progesterone, and LH, making option (a) the right choice.

Ans: (a)

The limitations of Mendeleev's periodic table are as follows:

1. Anomalous pairs, e.g. Co is placed before Ni even though Ni has a lower atomic mass.

2. Position of hydrogen is controversial as it resembles both alkali metals and halogens in many characteristics.

3. Position of isotopes is controversial as they were given the same slot, even though they have different atomic masses.
However, the noble gases could be accommodated in Mendeleev's table when they were discovered without disturbing the existing order.

Ans: (c)

On moving from left to right across the periods of the periodic table, the atomic radius decreases and hence the ionisation energy increases.

Therefore, the tendency to lose the valence electrons, i.e. the electropositive character decreases.

Hence, option (c) is incorrect.

Ans: (a)

• The impure metal acts as the anode in the electrolytic refining process.
• A thin strip of pure metal serves as the cathode.
• The electrolyte contains a solution of metal salt, which facilitates the process.
• As current flows, the pure metal from the anode dissolves into the electrolyte.
• Simultaneously, an equivalent amount of pure metal is deposited on the cathode, while the insoluble impurities settle at the bottom, referred to as anode mud.