21. What is the main component of the Sun’s mass?
(A) hydrogen
B. nitrogen
C. carbon dioxide
D. helium
22. What is a bidirectional semiconductor device?
A) Diode
B) BJT
C) SCR
D) TRIAC
23. What is the proportion of Hydrogen to Helium in the Sun?
A. 3:01
B. 1:01
C. 3:02
D. 3:04
24. What is the term for the rate of doing work of a body?
A. Force
B. Area
C. Power
D. None
25. What is ombrophobia the fear of?
A. Smog
B. Snow
C. None of these
D. Rain
26. What is the unit of mass?
A. Kg
B. Km
C. W
D. N
27. In which medium does sound travel at its maximum speed?
A. Gas
B. Liquid
C. Same in all
D. Solid
28. What does a deficiency of Vitamin-D result in?
A. Night blindness
B. Rickets
C. Scurvy
D. Hair fall
29. What is the SI unit of charge?
A. Ampere
B. Coulomb
C. Ohm’s
D. Volt
30. What is it called when sound is reflected from the floor or a wall, mixing with the original sound and altering its characteristics?
A. Sound
B. Reverberation
C. Echo
D. Noise
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