Class X (CBSE 2019) Science All India (Set-1)

General Instructions:

1. The question paper comprises five sections, A, B, C, D and E. You are to attempt all the sections.
2. All questions are compulsory.
3. Internal choice is given in sections B, C, D and E.
4. Question numbers 1 and 2 in Section A are one mark questions. They are to be answered in one word or in one sentence.
5. Question numbers 3 to 5 in Section B are two-marks questions. These are to be answered in about 30 words each.
6. Question numbers 6 to 15 in Section C are three-marks questions. These are to be answered in about 50 words each.
7. Question numbers 16 to 21 in Section D are five-marks questions. These are to be answered in about 70 words each.
8. Question numbers 22 to 27 in Section E are based on practical skills. Each question is a two marks question. These are to be answered in brief.

Question 1

State Ohm's law.

SOLUTION:

According to Ohm's law, the electric current flowing through a metallic wire is directly proportional to the potential difference V, across its ends provided its temperature remains the same.

In other words, <math>V \propto I</math>

Or, <math>V = RI</math>

Where, R is a constant of proportionality called resistance of the resistor, it tends to resist the flow of charge through a conducting wire. Its SI unit is Ohm <math>(\Omega)</math>.

Question 2

Name any two nutrients that the spent slurry has in the biogas plant.

SOLUTION:

Two nutrients that the spent slurry has in the biogas plants are nitrogen and phosphorous.

Question 3

Draw a labelled ray diagram to show the path of the reflected ray corresponding to an incident ray of light parallel to the principal axis of a convex mirror. Mark the angle of incidence and angle of reflection on it.

SOLUTION:

Reflected ray

Incident ray <math>i = incident angle</math>

<math>r = \text{reflected angle}</math> P Convex mirror

Question 4

A compass needle is placed near a current carrying straight conductor. State your observation for the following cases and give reasons for the same in each case:

1. Magnitude of electric current is increased.

(b) The compass needle is displaced away from the conductor.

SOLUTION:

1. Deflection of compass needle increases- Magnetic field strength is directly proportional to the amount of current.

(b) Deflection of compass needle decreases-Magnetic field strength is inversely proportional to the distance from the wire.

Question 5

Out of HCl and CH₃COOH, which one is a weak acid and why? Explain with the help of an example.