10 Science Solved Sample Paper 4 – Page 2
Question: 7. A student while studying the force experienced by a current carrying conductor in a magnetic field records the following observations:
(1). The force experienced by the conductor increases as the current is increased.
(2). The force experienced by the conductor decreases as the strength of the magnetic field is increased.
Which of the two observations is correct and why? 
Answer: Observation (1). is correct as the force experienced by the current carrying conductor is directly proportional to magnitude of the current passing through the conductor.
What is an electromagnet? How is it different from a permanent magnet? State two uses of electromagnet. (3 marks)
Question: Write commercial and SI units of energy. Calculate the cost of electric energy consumed by an electric heater rated with 50 W used for 2 hours daily in the month of April. The cost of one unit of electric energy is Rs. 5. 
Answer: Commercial unit of energy is kWh; SI unit of energy is Joule; P = 50 Watt ⇒ 50/1000 kW
t = 2 hrs., Number of days = 30 days
E = p × t × number of days. E = 50/1000 × 2 × 30 ⇒ 3 kWH (3 Unit)
Cost of 1 unit = Rs 5.00, ∴ Cost of electric energy consumed = Rs. 5 × 3 = Rs. 15
(1). What is the function of earth wire in electrical instruments?
(2). Explain what is short circuiting and electric supply.
(3). What is the usual current rating of the fuse wire in the line to feed?
Question: 9. What is corrosion? Why aluminium sheets do not corrode easily? Write two necessary conditions for corrosion to take place. 
Question: 10. Mention pf each one of these components of the transport system in plants. State one specific function of each one of these components. 
Answer: These two components are: (1). Phloem (2). Xylem.
Phloem transport food prepared by the leaves to other parts of the plant.
Xylem transports water and soluble mineral ions from roots to the leaves in the upward direction.
Question: 11. An ester has molecular formula C4H8O2. Write its structural formula. What happens when this ester is heated in the presence of aqueous sodium hydroxide solution? Write the chemical equation for the reaction and also state the chemical name of the products formed.