i. The number of base units in SI are?




... Answer is (c) 7
 A base unit is a unit adopted for measurement of a base quantity. The System of International (SI) consists of seven base units include: metre, kilogram, second, ampere, Kelvin, mole and candela (The units of the Base Quantity mass, length, time, electric current, temperature, amount of substance and luminous intensity respectively).


ii. Which one of the following unit is not a derived unit ?




... Answer is (b) kilogram
 Kilogram is a base unit for the measurement of the base quantity Mass, while the other pascal, newton and watt are derived units.


iii. Amount of a substance in terms of numbers is measured in ?




... Answer is (d) Mole
 In SI units amount of a substance is the base quantity and measured in mole.


iv. An Interval of 200 µs is equivalent to ?




... Answer is (c) 2 x 10^-4 s
 Solution: 200 µs = 2 x 10^2 x 10^-6 s (as 1 µ= 10-6) = 2 x 10^-4 s


v. Which one of the following is the smallest quality ?




... Answer is (d) 5000 ng
 Solution: 0.01 g = (1 / 100 ) g 2 mg = (2 / 1000 ) g 100 µg = (1 / 10000 ) g 5000 ng = (5 / 1000000) g (as 1 nino "n"= 10^-9) So the smallest value is 5000 ng.


vi. Which instrument is the most suitable to measure the internal diameter of a test tube ?




... Answer is (b) vernier calipers
 Vernier Calliper has both internal and external jaw. The Internal jaws of a vernier is used to measure the internal diameter of hollow tube or cylinder, while the from the outer jaws is for to measure the outer diameter of substances like a sphere.


vii. A student claimed the diameter of a wire as 1.032 cm using Vernier Callipers up to what extent do you agree with it ?:




... Answer is (c) 1.03cm
 A Vernier calliper has a least count of 0.01 cm (2 decimal place). So we can measure diameter only up to 2 decimal place i.e 1.03. Therefore reading as 1.032cm is impossible. V = 60 cm/sec.


viii. A measuring cylinder is used to measure ?




... Answer is (c) volume
 A measuring cylinder is a laboratory equipment used to measure the volume of a liquid.


ix. A student noted the thickness of glass sheet using screw gauge. On the main scale, it reads 3 divisions while 8th division on the circular scale coincides with index line. Its thickness is:




... Answer is (b) 3.08 cm
Solution: Main scale reading Screw gauge = 3 mm Coinciding division of Circular Scale = n = 8 Least count of screw gauge = 0.01 mm Thickness of wire = Main scale reading + n × Least Count = 3+8×0.01=3.08 mm
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