Q. The most suitable instrument for measuring the size of an atom is. Electron microscopeVernier calliperOptical MicroscopeScrew gauge Answer: Electron microscope

Q. Torr’ is the unit of pressurevolumedensityflux Answer: pressure

Q.14. The numbers 5.355 and 5.345 on rounding off to 3 significant figures will give 5.35 and5.345.36 and5.355.35 and5.355.36 and5.34 Answer: 5.36 and5.34

Q. The respective number of significant figures for the numbers 23.023, 0.0003 and 2.1×10-3 are 5, 1, 25, 1, 55, 5, 24, 4, 2 Answer: 5, 1, 2

Q. Which two of the following five physical parameters have the same dimensions? I. Energy density II. Refractive index III. Dielectric constant IV. Young’s modulus V. Magnetic field I and IVIII and VI and III and V Answer: I and IV

Q. The length, breadth and height of a rectangular block of wood were measured to be l = 12.13 ± 0.02 cm, b = 8.16 ± 0.01cm and h = 3.46 ± 0.01cm. 0.88%0.58%0.78%0.68% Answer: 0.58%

Q. The moon is observed from two diametrically opposite points A and B on earth. The angle θ subtended at the moon by the two directions of observation is 1°54′; given that the diameter of the earth to be about 1.276×107m. Compute the distance of the moon from the earth. 4.5x 109 m3.83 x108 ...

Q. A student measures the time period of 100 oscillations of a simple pendulum four times. The data set is 90s, 91s, 92s and 95s. If the minimum division in the measuring clock is 1s, then the reported mean time should be (92 ± 2)s(92 ± 5)s(92 ± 1.8)s(92 ± 3)s Answer: (92 ± 2)s

Q. A student measured the length of a rod and wrote it as 3.50 cm. Which instrument did he use to measure it? Ameter scaleA vernier calliper where the 10 divisions in vernier scale matches with 9 divisions in main scale and main scale has 10 divisions in 1 cmA screw gauge having 100 divisions ...

Q. The ratio of the volume of the atom to the volume of the nucleus is of the order of 1015102510201010 Answer: 1015

Q. The damping force on an oscillator is directly proportional to the velocity. The unit of the constant of proportionality is kg-ms-1kg-ms-2kgs-1kg-s Answer: kgs-1

Q. Which of the following measurement is most precise? 5.00 mm5.00 cm5.00 m5.00 km Answer: 5.00 mm