# IJSO (Indian Junior Science Olympiad) Mock Paper – Mathematics, Physics, Chemistry and Biology Part 3

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25. The speed of a boat is 5 km/hr. is still water. It crosses a river of width 1km along the shortest possible path in 15 minutes. The velocity of river water is:

A. 4 km/hr.

B. 3 km/hr.

C. 5 km/hr.

D. 2 km/hr.

26. The ratio of one micron to one nanometer is

A.

B.

C.

D.

27. The density of a cube is measured by measuring its mass and the length of its side. If the maximum errors in the measurement of mass and length are 4 % and 3 % respectively, the maximum error in the measurement of the density is:

A. 9 %

B. 13 %

C. 12 %

D. 7 %

28. A model rocket is attached to tile end of a 2.0 in long rigid rod. The other end of the rod rotates on a frictionless pivot, causing tile rocket to move in a horizontal circle (see fig.) . Tile rocket accelerates at starting from rest, then runs out of fuel at . Tile rocket՚s angular velocity, in revolution per minute (rpm) , when it runs out of fuel is

A. 48

B. 36

C. 54

D. 64

29. Density of wood is 0.5 g/cc in the CGS system of units. The corresponding value in MKS units is:

A. 5000

B. 5

C. 0.5

D. 500

30. Driver of a train travelling at 115 km/hr. sees on the same track, 100 m in front of him. A slow train travelling in the same direction at 25 km/hr. The least retardation that must be applied to faster train to avoid a collision is:

A.

B.

C.

D.

31. Vernier calipers have 20 divisions on its Vernier scale which coincide with 19 divisions on the main scale. Least count of the instrument is 0.1 mm. The main scale division is:

A. 0.5 mm

B. 1 mm

C. 2 mm

D. 0.25 mm

32. A particle moves iii a circle of radius 5cm vit1i constant speed and time period . The acceleration of the particle is:

A.

B.

C.

D.

33. Which of the following does not have the same unit as others?

A. Watt-sec

B. Kilowatt-hour

C. eV

D. J-sec

34. A unit less quantity:

A. Does not exist

B. Always has a nonzero dimension

C. Never has a nonzero dimension

D. May have a nonzero dimension

35. If the sum of two unit vectors is a unit vector, then the magnitude of their difference is:

A.

B.

C.

D.

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