Ruby
Sapphire
Diamond
Emerald
What is the unit for measuring the amplitude of a sound ?
Reading of a barometer going down is an indication of
Decibel is the unit for
One fathom is equal to
Fathom is the unit of
Light year is a measurement of
Very small time intervals are accurately measure by
One kilometre is equal to how many miles
kilohertz is a unit which measures
One horse power is equal to
