CBSE Science Important Question 2021

 

1. Write S.I. unit of resistivity. ( 1 Marks)
2. Study the following electric circuit of 3 Volt battery and find (i) the current flowing in the circuit and (ii) the potential difference across 10 Ω resistor. ( 3 Marks)

3. Find the current drawn from the battery by the network of four resistors Shown in the figure ( 3 Marks)

 

4. (a) Write two points of difference between electric energy and electric power. (b) Out of 60 W and 40 W lamps, which one has higher electrical resistance when in use? (c) What is the commercial unit of electric energy? Convert it into joules. ( 5 Marks)
5. Define 1 volt. Express it in terms of SI unit of work and charge calculate the amount of energy consumed in carrying a charge of 1 coulomb through a battery of 3 V. (3 Marks)
6. An electric bulb of resistance 200Ω draws a current of 1 Ampere. Calculate the power of the bulb the potential difference at its ends and the energy in kWh consumed burning it for 5h. ( 3 Marks)
7. A 9Ω resistance is cut into three equal parts and connected in parallel. Find the equivalent resistance of the combination. ( 2 Marks)
8. How is an ammeter connected in a circuit to measure current flowing through it? ( 1 Marks)
9. Give the characteristic tests for the following gases (a) CO₂ (b) H₂ ( 4 Marks)
10. What are strong and weak acids? In the following list of acids, separate strong acids from weak acids. Hydrochloric acid, citric acid, acetic acid, nitric acid, formic acid, sulphuric acid ( 3 Marks)
11. An element is placed in 2nd Group and 3rd Period of the Periodic Table, burns in presence of oxygen to form a basic oxide. (a) Identify the element (b) Write the electronic configuration (c) Write the balanced equation when it burns in the presence of air (d) Write a balanced equation when this oxide is dissolved in water (e) Draw the electron dot structure for the formation of this oxide ( 5 Marks)
12. Draw the diagram of alimentary canal of man and label the following parts. Mouth, Oesophagus, Stomach, Intestine (4 Marks)
13. What are various ways to avoid pregnancy? Elaborate any one method ( 4 Marks)