30. The prefix ‘nano-‘ denotes a factor of:
A) 10^-6
B) 10^-9
C) 10^-12
D) 10^-15
31. Which physical quantity is measured in Lux?
A) Luminous flux
B) Luminous intensity
C) Illuminance
D) Luminance
32. The SI unit of radioactivity is:
A) Becquerel
B) Curie
C) Gray
D) Sievert
33. Which of the following is a fundamental quantity?
A) Volume
B) Density
C) Time
D) Speed
34. The unit of luminous flux is:
A) Candela
B) Lumen
C) Lux
D) Watt
35. Which instrument is used to measure relative humidity?
A) Barometer
B) Hygrometer
C) Anemometer
D) Pyrometer
36. The prefix ‘pico-‘ denotes a factor of:
A) 10^-9
B) 10^-12
C) 10^-15
D) 10^-18
37. Which physical quantity is measured in Henrys?
A) Capacitance
B) Inductance
C) Resistance
D) Conductance
38. How many significant figures are in the number 0.00450?
A) 2
B) 3
C) 4
D) 5
39. Which of the following numbers has 4 significant figures?
A) 0.003402
B) 120.0
C) 45000
D) 0.00045
40. What is the number of significant figures in 6.02 × 10²³?
A) 2
B) 3
C) 5
D) 6