Q14. In domestic electric circuits the wiring with 15 A current rating is for the electric devices which have (a) higher power ratings such as geyser. (b) lower power ratings such as fan. (c) metallic bodies and low power ratings. (d) non-metallic bodies and low power ratings.

(a) higher power ratings such as geyser.

Q20. These consist of two statements – Assertion (A) and Reason (R). Answer this question selecting the appropriate option given below: Assertion (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. (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.

(a) Both (A) and (R) are true and (R) is the correct explanation of (A).

Q31. Give reasons for the following: (a) Danger signals installed at airports and at the top of tall buildings are of red colour. (b) The sky appears dark to the passengers flying at very high altitudes. (c) The path of a beam of light passing through a colloidal solution is visible.

Red is scattered least, so it is seen from far; almost no scattering occurs at high altitude; colloidal particles scatter the beam.

Q32(b). (i) Draw the pattern of magnetic field lines of (1) a current carrying solenoid (2) a bar magnet (ii) List two distinguishing features between the two fields.

A solenoid's field is temporary, controllable and reversible; a bar magnet's field is permanent, fixed and not reversible.

CBSE Class 10 Science 2023 — Paper 31/1/1

80 marks · 3 hours · 39 questions (46 with the OR choices)

34 of its 46 questions also appear in 31/1/2 or 31/1/3; 12 are only in this paper.

Take this paper as a timed mock

Free with an account: the board's time limit, marking at the end, and the answer to every question.

Questions 1–20 · 1 mark each

Q1 1 mark

Also in 31/1/2 (Q7), 31/1/3 (Q2)

This question is in the full bank. Sign up free to see it.
Q2 1 mark

Also in 31/1/2 (Q6), 31/1/3 (Q1)

This question is in the full bank. Sign up free to see it.
Q3 1 mark

Also in 31/1/2 (Q5), 31/1/3 (Q4)

This question is in the full bank. Sign up free to see it.
Q4 1 mark

Also in 31/1/2 (Q4), 31/1/3 (Q3)

This question is in the full bank. Sign up free to see it.
Q5 1 mark

This question is in the full bank. Sign up free to see it.
Q6 1 mark

Also in 31/1/2 (Q2), 31/1/3 (Q5)

This question is in the full bank. Sign up free to see it.
Q7 1 mark

Also in 31/1/2 (Q1), 31/1/3 (Q6)

This question is in the full bank. Sign up free to see it.
Q8 1 mark

Also in 31/1/2 (Q12), 31/1/3 (Q9)

This question is in the full bank. Sign up free to see it.
Q9 1 mark

Also in 31/1/2 (Q11), 31/1/3 (Q8)

This question is in the full bank. Sign up free to see it.
Q10 1 mark

Also in 31/1/2 (Q10), 31/1/3 (Q12)

This question is in the full bank. Sign up free to see it.
Q11 1 mark

Also in 31/1/2 (Q9), 31/1/3 (Q11)

This question is in the full bank. Sign up free to see it.
Q12 1 mark

This question is in the full bank. Sign up free to see it.
Q13 1 mark

Also in 31/1/2 (Q16), 31/1/3 (Q14)
If four identical resistors, of resistance 8 ohm, are first connected in series so as to give an effective resistance $R_{s}$ , and then connected in parallel so as to give an effective resistance $R_{p}$ , then the ratio $\frac{R _{s}}{R _{p}}$ is
1. (a) $32$
2. (b) $2$
3. (c) $0.5$
4. (d) $16$
Show answer

(d) $16$

Step-by-step solution →
Q14 1 mark

Also in 31/1/2 (Q15), 31/1/3 (Q13)
In domestic electric circuits the wiring with 15 A current rating is for the electric devices which have
1. (a)higher power ratings such as geyser.
2. (b)lower power ratings such as fan.
3. (c)metallic bodies and low power ratings.
4. (d)non-metallic bodies and low power ratings.
Show answer

(a) higher power ratings such as geyser.

Step-by-step solution →
Q15 1 mark
In 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 :
1. (a) $0.15$ V and $1.6$ V
2. (b) $0.05$ V and $1.6$ V
3. (c) $0.15$ V and $1.8$ V
4. (d) $0.05$ V and $1.8$ V
Show answer

(c) $0.15$ V and $1.8$ V

Step-by-step solution →
Q16 1 mark

Also in 31/1/2 (Q13), 31/1/3 (Q15)
The resultant magnetic field at point 'P' situated midway between two parallel wires (placed horizontally) each carrying a steady current I is
1. (a)in the same direction as the current in the wires.
2. (b)in the vertically upward direction.
3. (c)zero
4. (d)in the vertically downward direction.
Show answer

(c) zero

Step-by-step solution →
Q17 1 mark

Also in 31/1/2 (Q20), 31/1/3 (Q18)

This question is in the full bank. Sign up free to see it.
Q18 1 mark

Also in 31/1/2 (Q19), 31/1/3 (Q17)

This question is in the full bank. Sign up free to see it.
Q19 1 mark

This question is in the full bank. Sign up free to see it.
Q20 1 mark

Also in 31/1/2 (Q17), 31/1/3 (Q19)
These consist of two statements – Assertion (A) and Reason (R). Answer this question selecting the appropriate option given below :
Assertion (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.
1. (a)Both (A) and (R) are true and (R) is the correct explanation of (A).
2. (b)Both (A) and (R) are true, but (R) is not the correct explanation of (A).
3. (c)(A) is true, but (R) is false.
4. (d)(A) is false, but (R) is true.
Show answer

(a) Both (A) and (R) are true and (R) is the correct explanation of (A).

Step-by-step solution →

Questions 21–26 · 2 marks each

Q21(a) 2 marks

Also in 31/1/2 (Q26(a)), 31/1/3 (Q22(a))

This question is in the full bank. Sign up free to see it.

OR

Q21(b) 2 marks

Also in 31/1/2 (Q26(b)), 31/1/3 (Q22(b))

This question is in the full bank. Sign up free to see it.
Q22 2 marks

This question is in the full bank. Sign up free to see it.
Q23(a) 2 marks

This question is in the full bank. Sign up free to see it.

OR

Q23(b) 2 marks

This question is in the full bank. Sign up free to see it.
Q24 2 marks

Also in 31/1/2 (Q23), 31/1/3 (Q23)

This question is in the full bank. Sign up free to see it.
Q25(a) 2 marks

Also in 31/1/2 (Q22(a)), 31/1/3 (Q26(a))

A narrow beam XY of white light is passing through a glass prism ABC as shown in the diagram : Trace it on your answer sheet and show the path of the emergent beam as observed on the screen PQ. Name the phenomenon observed and state its cause.

Show answer

White light splits into seven colours on the screen: dispersion, caused by a different refractive index of glass for each colour.
The beam bends towards the base $B C$ at $A B$ , bends towards the base again at $A C$ , and leaves the prism as a band of seven colours that falls on the screen $P Q$ : red, orange, yellow, green, blue, indigo and violet, with red the least deviated (nearest the apex side of the band) and violet the most deviated (nearest the base side). The phenomenon is **dispersion** of light. Cause: white light is a mixture of seven colours and the refractive index of the glass is different for each of them - largest for violet and smallest for red. Each colour therefore travels at its own speed in glass, is refracted through its own angle and is deviated by its own amount, so the colours come out along different directions and separate.

Step-by-step solution →

OR
Q25(b) 2 marks

Also in 31/1/2 (Q22(b)), 31/1/3 (Q26(b))
It is observed that the power of an eye to see nearby objects as well as far off objects diminishes with age.
1. (i)Give reason for the above statement.
2. (ii)Name the defect that is likely to arise in the eyes in such a condition.
3. (iii)Draw a labelled ray diagram to show the type of corrective lens used for restoring the vision of such an eye.
Show answer

With age the ciliary muscles weaken and the lens loses flexibility; presbyopia, corrected by a bi-focal lens.
(i) With age the ciliary muscles become weak and the eye lens loses its flexibility, so the eye lens can no longer change its curvature freely. The power of accommodation of the eye therefore decreases: the near point recedes and distant vision may also be affected. (ii) The defect is presbyopia (old-age long-sightedness). (iii) The corrective lens is a **bi-focal** lens - a single spectacle lens made of two parts. Its upper portion is a concave (diverging) lens, which is used for distant vision, and its lower portion is a convex (converging) lens, which is used for near vision.

Step-by-step solution →
Q26 2 marks

This question is in the full bank. Sign up free to see it.

Questions 27–33 · 3 marks each

Q27 3 marks

Also in 31/1/2 (Q33), 31/1/3 (Q28)

This question is in the full bank. Sign up free to see it.
Q28 3 marks

This question is in the full bank. Sign up free to see it.
Q29(a) 3 marks

Also in 31/1/2 (Q31(a)), 31/1/3 (Q30(a))

This question is in the full bank. Sign up free to see it.

OR

Q29(b) 3 marks

Also in 31/1/2 (Q31(b)), 31/1/3 (Q30(b))

This question is in the full bank. Sign up free to see it.
Q30 3 marks
1. (a)Complete the following ray diagram to show the formation of image :
2. (b)Mention the nature, position and size of the image formed in this case.
3. (c)State the sign of the image distance in this case using the Cartesian sign convention.
Show answer

The image is virtual, erect and diminished, behind the mirror between P and the focus, and the image distance $v$ is positive.
(a) Ray 1, being parallel to the principal axis, is reflected away from the axis so that its backward extension passes through the principal focus (the point marked $R$ ). Ray 2, being directed towards the centre of curvature $C$ , strikes the mirror along the normal and is reflected back along the same path. The two reflected rays diverge, so they are produced backwards; their dashed extensions meet behind the mirror, between $P$ and $R$ , and that is where the image $A^{'} B^{'}$ is formed. (b) Nature: virtual and erect. Position: behind the mirror, between the pole $P$ and the principal focus (the point marked $R$ ). Size: diminished, i.e. smaller than the object. (c) The image distance $v$ is **positive**, because the image lies behind the mirror, on the same side as the direction in which the incident light travels.

Step-by-step solution →
Q31 3 marks
Give reasons for the following :
1. (a)Danger signals installed at airports and at the top of tall buildings are of red colour.
2. (b)The sky appears dark to the passengers flying at very high altitudes.
3. (c)The path of a beam of light passing through a colloidal solution is visible.
Show answer

Red is scattered least, so it is seen from far; almost no scattering occurs at high altitude; colloidal particles scatter the beam.
(a) Of all the colours of visible light, red has the longest wavelength, and the scattering of light falls off steeply as the wavelength increases. Red light is therefore scattered the least by the fog, smoke and dust particles in the air, so it travels the farthest and remains clearly visible from a great distance even in hazy weather. That is why danger signals are made red. (b) The blue colour of the sky is sunlight scattered towards us by the molecules and particles of the atmosphere. At very high altitudes the atmosphere is extremely thin and there are almost no molecules or dust particles to scatter the sunlight, so practically no scattered light reaches the passengers and the sky appears dark. (c) The particles of a colloidal solution are large enough to scatter light. As the beam passes through, light is scattered sideways from every point of its path and some of it reaches the eye, so the path of the beam becomes visible. This scattering of light by a colloid is called the Tyndall effect.

Step-by-step solution →
Q32(a) 3 marks

Also in 31/1/2 (Q28(a)), 31/1/3 (Q31(a))
1. (i)State the rule used to find the force acting on a current carrying conductor placed in a magnetic field.
2. (ii)Given below are three diagrams showing entry of an electron in a magnetic field. Identify the case in which the force will be (1) maximum and (2) minimum respectively. Give reason for your answer.
Show answer

Fleming's left-hand rule; the force is maximum in case (i), where the electron enters at $9 0^{\circ}$ to the field, and zero in case (iii).
(i) Fleming's left-hand rule. Stretch the thumb, the forefinger and the middle finger of the left hand so that they are mutually perpendicular. If the forefinger points in the direction of the magnetic field and the middle finger in the direction of the current, then the thumb gives the direction of the force acting on the conductor. (ii) (1) The force is **maximum** in case (i), because there the electron enters at right angles ( $9 0^{\circ}$ ) to the magnetic field, and the force $F = q v B sin θ$ is greatest when $sin θ = 1$ . (2) The force is **minimum** (zero) in case (iii), because there the electron moves parallel to the magnetic field, so $θ = 0^{\circ}$ and $sin θ = 0$ . In case (ii) the electron enters obliquely, so the force lies between these two values.

Step-by-step solution →
OR
Q32(b) 3 marks

Also in 31/1/2 (Q28(b)), 31/1/3 (Q31(b))
(i) Draw the pattern of magnetic field lines of
1. (1)a current carrying solenoid
2. (2)a bar magnet (ii) List two distinguishing features between the two fields.
Show answer

A solenoid's field is temporary, controllable and reversible; a bar magnet's field is permanent, fixed and not reversible.
(i) (1) Solenoid: the field lines inside the coil are straight, parallel and evenly spaced, running along the axis from one end to the other, which shows that the field inside is uniform; outside, they come out of one end, curve round the coil and go in at the other end, forming closed loops. The end the lines come out of is the north pole and the end they enter is the south pole. (2) Bar magnet: the field lines come out of the north pole, curve round outside the magnet and enter the south pole, continuing inside the magnet from south to north so that every line is a closed loop. They are crowded near the poles, where the field is strong, and far apart away from the magnet, where it is weak. No two field lines cross. (ii) Two distinguishing features: 1. The magnetic field of a solenoid is temporary and can be controlled - it lasts only while the current flows, and its strength can be increased by increasing the current, increasing the number of turns, or inserting a soft-iron core - whereas the field of a bar magnet is permanent and its strength is fixed. 2. The polarity of a solenoid can be reversed by reversing the direction of the current in it, whereas the polarity of a bar magnet cannot be reversed.

Step-by-step solution →
Q33(a) 3 marks

Also in 31/1/2 (Q27(a)), 31/1/3 (Q32(a))

This question is in the full bank. Sign up free to see it.

OR

Q33(b) 3 marks

Also in 31/1/2 (Q27(b)), 31/1/3 (Q32(b))

This question is in the full bank. Sign up free to see it.

Questions 34–36 · 5 marks each

Q34(a) 5 marks

Also in 31/1/2 (Q36(a)), 31/1/3 (Q36(a))

This question is in the full bank. Sign up free to see it.

OR

Q34(b) 5 marks

Also in 31/1/2 (Q36(b)), 31/1/3 (Q36(b))

This question is in the full bank. Sign up free to see it.
Q35 5 marks

This question is in the full bank. Sign up free to see it.
Q36 5 marks

Also in 31/1/2 (Q34), 31/1/3 (Q35)

This question is in the full bank. Sign up free to see it.

Questions 37–39 · 4 marks each

Q37 4 marks

Also in 31/1/2 (Q39), 31/1/3 (Q39)

This question is in the full bank. Sign up free to see it.
Q38 4 marks

Also in 31/1/2 (Q38), 31/1/3 (Q37)

This question is in the full bank. Sign up free to see it.
Q39 4 marks

Also in 31/1/2 (Q37), 31/1/3 (Q38)

This question is in the full bank. Sign up free to see it.

Other 2023 papers

All CBSE Class 10 Science papers →