More practice questions

4. Q4. Match the prefixes with their multiples (NCERT Exercise 1.15, page 26): micro, deca, mega, giga, femto; 10^⁶, 10^⁹, 10^⁻⁶, 10^⁻¹⁵, 10.

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   micro = 10^⁻⁶, deca = 10, mega = 10^⁶, giga = 10^⁹, femto = 10^⁻¹⁵.

5. Q5. A student has a mass of 60 kg. Find the student’s weight on the Earth (g = 9.8 m s^⁻²) and on the Moon (g = 1.62 m s^⁻²). Does the mass change?

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   Earth: 60 × 9.8 = 588 N. Moon: 60 × 1.62 ≈ 97 N. The mass stays 60 kg in both places; only the weight changes.

6. Q6. What is the SI unit of mass, and how is it defined (NCERT Exercise 1.14, page 26)?

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   The kilogram, kg. It is defined by taking the fixed numerical value of the Planck constant h to be 6.626 070 15 × 10^⁻³⁴ when expressed in J s, which is kg m^² s^⁻¹, with the metre and the second defined through c and the caesium frequency (NCERT Table 1.2, page 8).

7. Q7. Express 0.5 L in cm^³ and in m^³.

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   0.5 L = 0.5 × 1000 cm^³ = 500 cm^³ = 500 × 10^⁻⁶ m^³ = 5 × 10^⁻⁴ m^³.