Question 1

Question 1In the experimental setup given below, it is observed that on passing the gas produced in the reaction in the solution 'X' the solution 'X' first turn milky and then colourless.The option that justifies the above stated observation is that 'X' is aqueous calcium hydroxide andit turns milky due to carbon dioxide gas liberated in the reaction and after sometime it becomes colourless due to formation of calcium carbonate.it turns milky due to formation of calcium carbonate and on passing excess of carbon dioxide it becomes colourless due to formation of calcium hydrogen carbonate which is soluble in water.it turns milky due to passing of carbon dioxide through it. It turns colourless as on further passing carbon dioxide, sodium hydrogen carbonate is formed which is soluble in water.the carbon dioxide liberated during the reaction turns lime water milky due to formation of calcium hydrogen carbonate and after some time it turns colourless due to formation of calcium carbonate which is soluble in water.

Accepted Answer

it turns milky due to formation of calcium carbonate and on passing excess of carbon dioxide it becomes colourless due to formation of calcium hydrogen carbonate which is soluble in water.Reason — The reaction between sodium carbonate and HCl gas produces carbon dioxide gas.Na2CO3 + 2HCl (dil.) ⟶ 2NaCl + H2O + CO2Solution X is aq. calcium hydroxide which reacts with carbon dioxide gas and forms calcium carbonate, which turns the solution milky.Ca(OH)2 + CO2 ⟶ CaCO3 + H2OHowever, on passing excess carbon dioxide, the calcium hydrogen carbonate is formed, which is soluble in water and hence, the solution X becomes colourless.CaCO3 + H2O + CO2 ⟶ Ca(HCO3)2

Question 2

Question 2The emission of brown fumes in the given experimental set-up is due tothermal decomposition of lead nitrate which produces brown fumes of nitrogen dioxide.thermal decomposition of lead nitrate which produces brown fumes of lead oxide.oxidation of lead nitrate forming lead oxide and nitrogen dioxide.oxidation of lead nitrate forming lead oxide and oxygen.

Accepted Answer

thermal decomposition of lead nitrate which produces brown fumes of nitrogen dioxide.Reason — Thermal decomposition of lead nitrate takes place which produces brown fumes of nitrogen dioxide.2Pb(NO3)2 ⟶ 2PbO + 4NO2 + O2

Question 3

Question 3MnO2 + xHCl ⟶ MnCl2 + yH2O + zCl2In order to balance the above chemical equation, the values of x, y and z respectively are6, 2, 24, 1, 24, 2, 12, 2, 1

Accepted Answer

4, 2, 1Reason — The balanced equation is as follows:MnO2 + 4HCl ⟶ MnCl2 + 2H2O + Cl2

Question 4

Question 4The table below has information regarding pH and the nature (acidic/basic) of four different solutions. Which one of the options in the table is correct ?OptionSolutionColour of pH paperApproximate pH valueNature of solution(a)Lemon juiceOrange3Basic(b)Milk of magnesiaBlue10Basic(c)Gastric juiceRed6Acidic(d)Pure waterYellow7Neutral

Accepted Answer

Milk of magnesiaBlue10BasicReason — For lemon juice pH is 3 but colour of pH paper is orange and nature is given as basic which is incorrect. For Gastric juice, pH value of 6 is incorrect. For pure water, colour of pH paper is incorrect. It should be green not yellow.

Question 5

Question 5A metal 'X' is used in thermite process. When X is burnt in air it gives an amphoteric oxide 'Y'. 'X' and 'Y' are respectively :Fe and Fe2O3Al and Al2O3Fe and Fe3O4Al and Al3O4

Accepted Answer

Al and Al2O3Reason — Aluminium is used in thermite process. When aluminium is heated in oxygen it forms aluminium oxide which is amphoteric in nature .4Al + 3O2 ⟶ 2Al2O3

Question 6

Question 6Select washing soda from the following :NaHCO3Na2CO3.5H2ONa2CO3.10H2ONaOH

Accepted Answer

Na2CO3.10H2OReason — The formula of washing soda is : Na2CO3.10H2O

Question 7

Question 7Consider the structures of the three cyclic carbon compounds A, B and C given below and select the correct option from the following:A and C are isomers of hexane and B is benzene.A is an isomer of hexane, B is benzene and C is an isomer of hexene.A is a saturated cyclic hydrocarbon and B and C are unsaturated cyclic hydrocarbons.A is cyclohexane and B and C are the isomers of benzene.

Accepted Answer

A is a saturated cyclic hydrocarbon and B and C are unsaturated cyclic hydrocarbons.Reason — A is having all the single bonds hence it is a saturated hydrocarbon whereas B and C have double bonds so they are unsaturated cyclic hydrocarbons.

Question 8

Question 8An organism which breaks down the food material outside the body and then absorbs it isa plant parasite, Cascutaan animal parasite, Tapeworma bacteria, Rhizobiuma fungi, Rhizopus

Accepted Answer

a fungi, RhizopusReason — Fungi show extra-cellular digestion. The cell wall of fungi secretes enzymes that digest the food outside the body of fungi. The digested food is then absorbed by the fungi.

Question 9

Question 9Consider the following statements about small intestine and select the one which is NOT correct :The length of the small intestine in animals differs as it depends on the type of food they eat.The small intestine is the site of complete digestion of food.The small intestine receives secretions from liver and pancreas.The villi of the small intestine absorbs water from the unabsorbed food before it gets removed from the body via the anus.

Accepted Answer

The villi of the small intestine absorb water from the unabsorbed food before it gets removed from the body via the anus.Reason — The villi of the small intestine absorbs digested food. Excess water is absorbed in large intestine.

Question 10

Question 10The statement that correctly describes the characteristic(s) of a gene is :In individuals of a given species, a specific gene is located on a particular chromosome.A gene is not the information source for making proteins in the cell.Each chromosome has only one gene located all along its length.All the inherited traits in human beings are not controlled by genes.

Accepted Answer

In individuals of a given species, a specific gene is located on a particular chromosome.Reason— In individuals of a given species, each gene has a fixed locus on a specific chromosome.

Question 11

Question 11Select from the following the correct statement about tropic movement in plants:It is due to stimulus of touch and temperature.It does not depend upon the direction of stimulus received.It is observed only in roots and not in stems.It is a growth related movement.

Accepted Answer

It is a growth related movement.Reason — Tropic movement in plants is related to growth. It occurs in stem as well as roots. It is affected by touch, gravitation and light.

Question 12

Question 12Select the INCORRECT match (between the plant and its vegetative part) from the following :Bryophyllum, leafPotato, stemMoney-plant, stemRose, root

Accepted Answer

Rose, rootReason— Rose is propagated by stem.

Question 13

Question 13If four identical resistors, of resistance 8 ohm, are first connected in series so as to give an effective resistance Rs, and then connected in parallel so as to give an effective resistance Rp then the ratio RsRp\dfrac{R_s}{R_p}Rp​Rs​​ is3220.516

Accepted Answer

16Reason — Four identical resistors of resistance 8 Ω are connected in series :So, Rs = 8+8+8+8 = 32 ΩWhen connected in parallel:1Rp\dfrac{1}{R_p}Rp​1​ = 18\dfrac{1}{8}81​ + 18\dfrac{1}{8}81​ + 18\dfrac{1}{8}81​ + 18\dfrac{1}{8}81​1Rp\dfrac{1}{R_p}Rp​1​ = 1+1+1+18\dfrac{1+1+1+1}{8}81+1+1+1​ = 48\dfrac{4}{8}84​ = 12\dfrac{1}{2}21​So, Rp = 2 ΩRsRp\dfrac{R_s}{R_p}Rp​Rs​​ = 322\dfrac{32}{2}232​ = 16

Question 14

Question 14In domestic electric circuits the wiring with 15 A current rating is for the electric devices which havehigher power ratings such as geyser.lower power ratings such as fan.metallic bodies and low power ratings.non-metallic bodies and low power ratings.

Accepted Answer

higher power ratings such as geyser.Reason — As P = i2RHence, in domestic electric circuits the wiring with 15 A current rating is for the electric devices which have higher power ratings such as geyser.

Question 15

Question 15In the following diagram, the position of the needle is shown on the scale of a voltmeter. The least count of the voltmeter and the reading shown by it respectively are :0.15 V and 1.6 V0.05 V and 1.6 V0.15 V and 1.8 V0.05 V and 1.8 V

Accepted Answer

0.15 V and 1.8 VReason — Least count of any scale is the value measured by a single division on it.10 div = 1.5 VSo, 1 div = 1.510\dfrac{1.5}{10}101.5​ = 0.15 VHence, least count = 0.15 VReading shown = least count x no. of div. = 0.15 x 12 = 1.8 VHence, Reading shown = 1.8 V

Question 16

Question 16The resultant magnetic field at point 'P' situated midway between two parallel wires (placed horizontally) each carrying a steady current I isin the same direction as the current in the wires.in the vertically upward direction.zeroin the vertically downward direction.

Accepted Answer

zeroReason — The magnetic fields produced at the midpoint P, by the currents flowing in the same direction in the two parallel wires will be equal in magnitude but opposite in direction.Hence, the resultant magnetic field at P will be zero.

Question 17

Question 17Assertion (A) : The colour of aqueous solution of copper sulphate turns colourless when a piece of lead is added to it.Reason (R) : Lead is more reactive than copper, and hence displaces copper from its salt solution.Both (A) and (R) are true and (R) is the correct explanation of (A).Both (A) and (R) are true, but (R) is not the correct explanation of (A).(A) is true, but (R) is false.(A) is false, but (R) is true.

Accepted Answer

Both (A) and (R) are true and (R) is the correct explanation of (A)Reason — When a piece of lead is added to an aqueous solution of copper sulphate, a displacement reaction takes place as lead is more reactive than copper hence lead displaces copper from the copper sulphate solution. The chemical equation for the reaction is:Pb + CuSO4 ⟶ PbSO4 + CuThis results in a colorless solution [PbSO4].

Question 18

Question 18Assertion (A) : Genes inherited from the parents decide the sex of a child.Reason (R) : X chromosome in a male child is inherited from his father.Both (A) and (R) are true and (R) is the correct explanation of (A).Both (A) and (R) are true, but (R) is not the correct explanation of (A).(A) is true, but (R) is false.(A) is false, but (R) is true.

Accepted Answer

(A) is true, but (R) 1s false.Reason — Sex of a child is decided by the chromosome (X or Y) of father that is inherited by the embryo. Genes on chromosome Y are responsible for male child.

Question 19

Question 19Assertion (A) : Blood clotting prevents excessive loss of blood.Reason (R) : Blood clotting is due to blood plasma and white blood cells present in the blood.Both (A) and (R) are true and (R) is the correct explanation of (A).Both (A) and (R) are true, but (R) is not the correct explanation of (A).(A) is true, but (R) is false.(A) is false, but (R) is true.

Accepted Answer

(A) is true, but (R) is false.Reason — Blood clotting is due to blood platelets, fibrinogen and Prothrombin.

Question 20

Question 20Assertion (A) : The strength of the magnetic field produced at the centre of a current carrying circular coil increases on increasing the number of turns in it.Reason (R) : The current in each circular turn has the same direction and the magnetic field due to each turn then just adds up.Both (A) and (R) are true and (R) is the correct explanation of (A).Both (A) and (R) are true, but (R) is not the correct explanation of (A).(A) is true, but (R) is false.(A) is false, but (R) is true.

Accepted Answer

Both (A) and (R) are true and (R) is the correct explanation of (A).Reason — Magnetic field strength is directly proportional to the number of turns of the circular coil. Hence, strength of the magnetic field increases on increasing the number of turns in it because current in each circular turn has the same direction and the magnetic field due to each turn then just adds up.

Solved 2023 Question Paper CBSE Class 10 Science

Section A (Objective Type Questions 1 Mark Each)

Section B (Very Short Answer Questions 2 Marks Each)

Section C (Short Answer Questions 3 Marks Each)

Section D (Long Answer Questions 5 Marks Each)

Section E (Source/Case Based Questions 4 Marks Each)