CBSE Class 10 Science NSO Olympiad MCQs with Answers Set B

Logical Reasoning

Question. Some of the letters are missing which are given in that order as one of the options below it. Select the correct option.
__ __ aba __ __ ba __ ab
A. abbba
B. abbab
C. baabb
D. bbab 
Answer : B

Question. In the given number series, how many 9s are there which are immediately preceded by a pair of numbers whose product is more than the product of the pair of numbers immediately following 9?
8 7 9 9 6 8 4 5 9 3 8 4 9 2 5 1 9 2 2 6 9 4 3 9 2 5 8 9 3 7
A. 4
B. 3
C. 6
D. 5
Answer : C

Question. If A is coded as 5, L as 16, J as 14 and so on.
Following this code, STAR is coded as 296, which of the following represents the code of JAILER?
A. 316
B. 395
C. 237
D. 553
Answer : A

Question. Abhishek said that he was born on 29 February 1900. What birthday will he celebrate in the year 2000?
A. 99th
B. 25th
C. 100th
D. Abhishek is lying
Answer : D

Question. If the image of a figure in water is seen as

Answer : D

Question. Study the Venn diagram carefully and select the correct statement.

A. There are some postgraduates who are rural people.
B. No professor is urban.
C. All post-graduates are rural.
D. All post-graduates are urban.
Answer : A

Question. Mr. Sinha has six children – Pankaj, Ravi, Varun, Amit, Vikas and Prateek. They all were born on 13th November, but each was born in a different year, during six consecutive years. It is also known that
(i) Pankaj is elder to Varun.
(ii) Ravi is elder to both Amit and Vikas.
(iii) Prateek is two years older than Amit.
(iv) Pankaj was born either in the year 2002 or 2003.
(v) The oldest member of the group was born in the year 2000.
(vi) Amit is elder to both Vikas and Varun.
Which of the following is the correct list of the group, from the youngest to the oldest?
A. Varun, Pankaj, Ravi, Amit, Vikas, Prateek
B. Varun, Vikas, Pankaj, Amit, Prateek, Ravi
C. Varun, Vikas, Amit, Prateek, Pankaj, Ravi
D. Varun, Vikas, Amit, Pankaj, Prateek, Ravi
Answer : D

Question. Select the pair that has a relationship similar to the pair in Fig. (X). The best answer is to be selected from a group of fairly close choices 

Answer : B

Question. A group of four policemen A, B, C and D is combining a circular park divided into sixteen plots. P, Q, R and K are the offenders who they have to catch after given moves. The figure below shows their positions. Note that the by-lanes are North-South and East-West.

If both A, B, C, D and P, Q, R, K moves clockwise three plots, then who would be positioned North-East and South-West from the given options respectively?
A. A and P
B. C and P
C. D and Q
D. B and R
Answer : A

Question. Find the missing number, if the given matrix follows a certain rule row-wise or column-wise.

A. 9
B. 7
C. 13
D. 11
Answer : D

Question. Select a figure from the options which will continue the series as established by the five problem figures.

Answer : D

Question. Six different faces of a cube are coloured in three different colours – black, green and blue. This cube is now cut into 216 smaller but identical cubes. If N is the number of cubes that is not coloured on any of its faces, then which of the following best describes the value of N ?
A. 125 < N < 130
B. 120 ≤ N ≤ 125
C. 115 ≤ N ≤ 120
D. 50 < N < 100
Answer : D

Question. There are seven figures, the first and last of which are un-numbered and the remaining are numbered as 1, 2, 3, 4 and 5. These seven figures form a series.
However, one of the five numbered figures does not fit into the series. Select the figure which does not fit into the series.

A. 1
B. 3
C. 4
D. 2
Answer : A

Question. Which of the following figures will complete the given figure matrix?

Answer : B

Question. A is the brother of B. B is the brother of C. D is the father of A. Which of the following statements cannot be definitely true?
A. B is the brother of A.
B. B is the son of D.
C. A is the brother of C.
D. C is the brother of A.
Answer : D

Science

Question. A network is constructed using five resistors, each of resistance R, and three switches K₁, K₂ and K₃.
Which switch combination will give rise to maximum total resistance between points X and Y?

      K1               K2           K3
A. Open         Closed     Open
B. Open         Closed     Closed
C. Closed      Closed     Closed
D. Closed      Open       Closed
Answer : A

Question. A constant current flows in a horizontal wire in the plane of the paper from west to east as shown in the given figure. The direction of magnetic field will be north to south, at a point______.

A. Directly above the wire
B. Directly below the wire
C. Located in the plane of the paper, on the north side of the wire
D. Located in the plane of the paper, on the south side of the wire.
Answer : A

Question. Read the given statements and select the correct option.
Statement 1 : A concave mirror and a convex lens both have the same focal length in air. When they are submerged in water, they will still have the same focal length.
Statement 2 : The refractive index of water is greater than the refractive index of air.
A. Both statements 1 and 2 are true and statement 2 is the correct explanation of statement 1.
B. Both statements 1 and 2 are true but statement 2 is not the correct explanation of statement 1.
C. Statement 1 is true but statement 2 is false.
D. Statement 1 is false but statement 2 is true.
Answer : D

Question. An explosion takes place at a distance of 3200 m away from a sound detector that detects only the sound coming from the ground.
The sound detector detects two sound signals at 0.64 s and 0.80 s after the explosion. Find the depth x of the soft ground.

A. 1200 m
B. 2400 m
C. 3600 m
D. 4800 m
Answer : A

Question. A concave mirror of focal length 10 cm is dipped in water as shown in the given figure.
Given that the refractive index of water is 4/3 and object S is placed on the principal axis of the concave mirror.
The final image formed by the system is at

A. 85/4 cm from water surface
B. 85/4 cm from mirror surface
C. 94/3 cm from water surface
D. 94/3 cm from mirror surface.
Answer : A

Question. An acrobat swings from point P to Q as shown in the given figure. The length of the swinging rod is 5 m. The minimum initial speed, the acrobat must have, at point P is (Take g = 10 N kg^–1)

A. 10 m s^–1
B. 20 m s^–1
C. 50 m s^–1
D. Cannot be determined
Answer : A

Question. A heater, a fan and a bulb are connected to the 12 V battery as shown in the given diagram.

The fan with a resistance of R has a potential difference of 6 V across it and a current of 1 A through it. The bulb has a current of 2 A flowing through it. Which of the following statements is true?
A. The voltage across the bulb is 6 V and its resistance is 2R.
B. The voltage across the bulb is 6 V and its resistance is 1/2 R.
C. The voltage across the heater is 6 V and its resistance is 2 R.
D. The voltage across the heater is 6 V and its resistance is 1/2 R.
Answer : B

Question. Which of the following statements is/are true regarding a typical solar cell?
(i) It develops a voltage of 0.5 to 1 volt.
(ii) It can produce only upto 0.5 W of electricity.
(iii) It is made from silicon.
(iv) Efficiency of solar cell is low.
(v) It is used for many scientific and technological applications.
A. (i), (ii) and (iii) only
B. (i), (iii) and (iv) only
C. (i), (iii), (iv) and (v) only
D. All of these
Answer : C

Question. Two identical balls, P and Q are being dropped from different levels of a building. If ball P takes twice the time than ball Q to reach the ground, then ______.
A. The distance travelled by ball P is half the distance travelled by ball Q
B. The distance travelled by ball P is twice the distance travelled by ball Q
C. The distance travelled by ball P is four times the distance travelled by ball Q
D. The distance travelled by ball P is eight times the distance travelled by ball Q
Answer : C

Question. A satellite moves in a circle around the Earth. The radius of this circle is equal to one half of the radius of the Moon's orbit. The satellite completes one revolution in
A. 1/2 lunar month
B. 2/3 lunar month
C. 21/2 lunar month
D. 2–3/2 lunar month
Answer : D

Question. O xide M is a colourless gas. It reacts with oxygen to form a reddish-brown gas, oxide N. The solubility of
oxides M and N in various solvents is shown below :

Which of the following statements is correct?
A. Oxide M is an acidic oxide.
B. Oxide M is an amphoteric oxide.
C. Oxide N is a basic oxide.
D. Oxide N is an acidic oxide.
Answer : D

Question. The boiling points of some gases found in air are given below :

If liquid mixture is fractionally distilled, the order of gases distilled out (starting from first) is _____.
A. Krypton, neon, nitrogen, oxygen
B. Neon, nitrogen, oxygen, krypton
C. Nitrogen, neon, oxygen, krypton
D. O xygen, neon, nitrogen, krypton
Answer : B

Question. How many of the total number of electrons in a molecule of ethyne C₂H₂ are not involved in bonding?
A. 4
B. 10
C. 6
D. 0
Answer : A

Question. Study the given graph carefully.

I. c and d contain same number of protons.
II. Pairs (a, b), ( f, g) and (i, j) are isobars.
III. Pairs (c, d) and (g, h) are isotopes.
IV. e and f have different number of neutrons.
The correct statements are
A. I, II and IV
B. I, III and IV
C. I and III
D. All of these
Answer : B

Question. Strips of metal X were dipped into two solutions as shown below :
A greyish metallic deposit was found on both strips.
Which of the following could be metal X?
A. Cu
B. Mg
C. Pb
D. F 
Answer : B

Question. A compound P contains two hydrogen, one sulphur and four oxygen atoms. Another compound Q contains five hydrogen, one oxygen and one nitrogen atoms. The formula of a new compound formed by the divalent anion of P and monovalent cation of Q is'

A. NH₄HSO₄
B. (NH₄)₂SO₃
C. NH₄HSO₃
D. (NH₄)₂SO₄
Answer : D

Question. A part of the periodic table is given below :

(The letters are not the actual chemical symbols of the elements.)
Choose the incorrect statement among the following.
A. Q and R combine together to form a compound, Q₂R₃.
B. N is a metal with valency 2 and L is a non-metal with valency 3.
C. G is the most reactive metal and H is the most reactive non-metal.
D. M forms ionic compounds and V is ver y reactive.
Answer : D

Question. Schematic atomic structures of four different

The incorrect representations are
A. I, II and IV
B. I, III and IV
C. III and IV
D. I and III
Answer : B

Question. In the following reactions ethanol is either a reactant or product.
I. Combustion of ethanol
II. Dehydration of ethanol to ethene
III. Fermentation of glucose
IV. O xidation of ethanol to ethanoic acid
The reactions in which water is also either a reactant or product are
A. I, III and IV
B. II, III and IV
C. I, II and IV
D. I and IV
Answer : C

Question. The melting and boiling points of three pure substances X, Y and Z are given in the table

At room temperature, 25°C
A. Z is a gas
B. X is a volatile liquid
C. Y is a solid
D. All are correct.
Answer : A

Question. Study carefully the key depicting the type of plant tissues :
Key :
Types of meristematic tissue – P, Q
Types of permanent simple tissue – R, S
Types of parenchymatous tissue – T, U
Identify these tissues (P to U) from the list of their functions given below.
(i) It provides mechanical support, elasticity and tensile strength to the body.
(ii) This tissue is responsible for linear growth of an organ.
(iii) It provides a protective covering around seeds and nuts.
(iv) It provides buoyancy to aquatic plants to help them float.
(v) It is responsible for growth of leaves and internodes.
(vi) It performs the process of photosynthesis.
    (i)   (ii)  (iii) (iv) (v)  (vi)
A. Q   S    T    R   U    P
B. S   Q    R    T   P    U
C. T   U    P    Q   S    R
D. P   Q    T    R   U    S
Answer : B

Question. Refer to the diagramshowing the vascular tissue from a dicotyledonous plant and answer the following question.
Which of the following statements correctly compares structures P and Q?

A. P has cell wall made of lignin, but Q has cell wall made of cellulose.
B. P transports substances only from roots to leaves, but Q transports substances in either direction.
C. P comprises cells that largely lack cytoplasm, but Q comprises cells that possess cytoplasm.
D. P contains water and mineral salts, while Q contains food substances in the form of starch.
Answer : B

Question. Cells without nucleoli die because they do not possess ______.
A. Centrioles and so are unable to undergo cell division
B. Lysosomes and so are unable to destroy worn out organelles
C. Mitochondria and so are unable to obtain energy
D. Ribosomes and so are unable to manufacture proteins.
Answer : D

Question. Pea plants can have smooth seeds or wrinkled seeds. One of the phenotypes is completely dominant over the other. A farmer decides to pollinate one flower of a plant with smooth seeds using pollen from a plant with wrinkled seeds. The resulting pea pod has all smooth seeds. Which of the following conclusion(s) can be drawn?
1. The allele for smooth seeds is dominant over that for wrinkled seeds.
2. The parent plant with smooth seeds is a homozygote.
3. The parent plant with wrinkled seeds is a homozygote.
A. 1 only
B. 2 only
C. 1 and 3
D. 1, 2 and 3
Answer : D

Direction : Refer to the food web given below to answer questions A and B.

Question a. A non-biodegradable insecticide known as DDT was sprayed onto the pine trees. In which of the following organisms would most of the DDT eventually accumulate?
A. Golden-crowned kinglet
B. Pine borer
C. Salamander
D. Snake
Answer : D

Question b. With reference to the given food web, which of the following statements is true?
A. There is only one organism that makes organic compounds from inorganic substances.
B. There is no such one organism that converts organic compounds into inorganic substances.
C. The inability of the oak tree to produce acorns would affect the red-tailed hawk more than the snake.
D. Removal of X would cause an increase in the population of all the organisms.
Answer : C

Question. The following data regarding two different plant species was obtained. data?
1. Plant Y is more likely to be wind-pollinated.
2. Plant Y is more likely to be self-pollinated than plant X.
3. Since plant Y has larger and heavier pollen, a larger mass of pollens must be produced by plant Y per unit time to achieve the same efficiency of pollination as plant X.
4. The stigma of plant X is likely to have a larger surface area than those of plant Y.
A. 4 only
B. 1 and 3
C. 2 and 4
D. 3 and 4
Answer : A

Question. Read the following statements (a - c) and select the option which correctly fills up the blanks in any two of the statements.
(a) (1) is a bacterial disease, while (2) is a viral disease.
(b) (3) is the mode of prevention of diseases.
(c) (4) and (5) are diseases which spread through sexual act.
A. (1)-Chicken pox, (2)-Typhoid, (4)-Syphilis, (5)-Cholera
B. (1)-Cholera, (2)-Chicken pox, (3)-Prophylaxis
C. (3)-Immunization, (4)-AIDS, (5)-Tuberculosis
D. (3)-Vaccination, (4)-Syphilis, (5)-Jaundice
Answer : B

Question. Study the given flowchart. Which of the following are the correct examples of W, X, Y and Z? 

        W                     X                         Y                      Z
A. Ulothrix            Marsilea            Selaginella         Cycas
B. Riccia              Marsilea            Cycas                 Ipomoea
C. Lycopodium    Marchantia        Pinus                  Ipomoea
D. Spirogyra        Dryopteris         Funaria               Pinus
Answer : B

Question. A student suggests that plant cells do not require mitochondria since they have chloroplasts. Which of the following statements would you use to convince him otherwise?
A. Having both chloroplasts and mitochondria would maximise the rate of photosynthesis.
B. Having both chloroplasts and mitochondria would maximise the rate of energy production.
C. Mitochondria would be necessary at night when chloroplasts are no longer able to photosynthesize.
D. The chemical energy stored in glucose cannot be efficiently utilized in the cell without mitochondria.
Answer : D

Achievers section

Question. The plot represents the flow of current through a wire at three different times. The ratio of charges flowing through the wire at different intervals is

A. 1 : 2 : 3
B. 1 : 1 : 1
C. 3 : 2 : 2
D. 2 : 3 : 3
Answer : B

Direction (Q. No. a & b): Refer to the given passage and answer the following questions.
Redox reactions are those in which oxidation and reduction take place simultaneously. Oxidation is the gain of oxygen or loss of hydrogen while reduction is the loss of oxygen or gain of hydrogen.
Those given off in the oxidation are taken on by another species in the reduction reaction.
A substance which helps the other substance to undergo oxidation is called an oxidising agent. Similarly, a substance which helps the other substance to undergo reduction is called a reducing agent.

Question a. In the reaction, MnO₂ + 4HCl → MnCl₂ + 2H₂O + Cl₂
A. HCl is reduced to Cl₂ whereas MnO₂ is oxidised to MnCl₂
B. HCl is oxidised to H2O whereas MnO₂ is reduced to MnCl₂
C. HCl is reduced to Cl₂ whereas MnO₂ is oxidised to H₂O
D. HCl is oxidised to Cl₂ whereas MnO₂ is reduced to MnCl₂
Answer : D

Question b. Which of the following statements about the given reaction are not correct?
Fe₂O₃ + 3CO → 2Fe + 3CO₂
I. Fe₂O₃ is getting oxidised to Fe.
II. Fe₂O₃ is acting as a reducing agent.
III. CO is acting as a reducing agent.
IV. CO is getting reduced to CO₂.
A. III only
B. I, II and IV
C. II and IV
D. I and III
Answer : B

Question. Refer to the diagram of the human digestive system to answer the following question.

What would be the likely consequence of swapping S and T i.e., from the stomach, food will pass through T to S?
A. The digestive enzymes would be denatured.
B. The intestinal contents would be highly alkaline and would damage the wall of T.
C. The intestinal contents would be too dry and unable to pass through S properly.
D. Water absorption would be highly reduced.
Answer : C

Question. The graph below shows the hormonal changes during a normal menstrual cycle. What would be a likely consequence if the hormone represented by graph Q is lacking in an adult female?

A. The uterine lining might not be sufficiently stable to support an implanted embryo.
B. Levels of the hormone represented by graph P would be higher than normal.
C. Fertilization of ovum would fail to occur.
D. There would be no significant effect since the functions of the hormones overlap.
Answer : A