2

Q1. A 2.16 g of a substance occupies 1.5 cm³. Its density to appropriate significant figure is:

• 1.44
• 1.4
• 1.444
• 1.5

Solution

There are 3 significant figures in measured mass whereas there are only 2 significant figures in measured volume. Hence density should be expressed to only 2 significant figures.

Q2. Find the option with 3 significant figures.

• 2.608 cm  
• 0.0268 m  
• 26.08 mm  
• 2.068 cm  

Solution

0.0268 have three significant figures where as 2.608 cm, 26.08 mm and 2.068 cm have four significant figures.        

Q3. Significant figures depend on ________ number of significant figures in given data.

• greatest number
• all
• least number
• none of the above

Solution

Significant figures depend only on least number of significant figures in given data.

Q4. The method used to measure the distance of a planet from the Earth is

• Galileo's method
•  Archimedes' method
• Newton's method
• Parallax method

Solution

The method used to measure the distance of a planet from the Earth is Parallax method.

Q5. A dimensionless quantity

• has no unit
• must have a unit
• might have a unit
• cannot exist

Solution

A dimensionless quantity might have a unit. For example, an angle has unit radians.

Q6. Magnitude of force F experienced by a certain object moving with speed v is given by F = Kv³, where K is a constant. The dimensions of K are

• [ML^-3T]
• [M^-2LT]
• [MLT^-2]
• [ML^-2T]

Solution

Q7. What is the dimension of (½)at²?

• length [L]  
• time[T]  
• length/time([L]/[T])  
• length/time² ([L]/[T²])  

Solution

½ a t² has the dimension of length since the dimension of acceleration is L/T² and multiplying it by T² leaves us with the dimension of length.

Q8. Relative error in Z, given that Z = 1/A² is:

• two times the error in A  
• the square of the error in A  
• half the error in A  
• square root of error in A.  

Solution

It is two times the error in A. If two quantities are multiplied or divided the relative error in the result is the sum of the relative errors in the multipliers.    

Q9. Parallax method is used to measure:

• very large distances
• very small distances
• very large angles
• very small angles

Solution

Parallax method is used to measure very large distances between terristial objects.

Q10. The order of magnitude of a number expressed in scientific notation is

• number of decimal places
• number of digit before decimal
• all digits in the number
• power of ten

Solution

The order of magnitude of a number expressed in scientific notation is power of ten.

Q11. The numbers of significant figures in 9.1 x10^-31 kg are:

• Three  
• Ten  
• Thirty one  
• Two  

Solution

As the power of 10 is irrelevant to the determination of significant figures hence, the numbers of significant figures are 2 (9 and 1).        

Q12. One angstrom is equal to __________ .

• 10^-10m
• 10^-11m
• 10^-12m
• 10^-9 m

Solution

One angstrom (1^o) is equivalent to 10^-10m.

Q13. Approximate ratio of 1 fermi to 1 angstrom is ..............

• 10^-15m
• 10^-5m
• 10^-6m
• 10^-9m

Solution

1 fermi = 10^-15 m, 1angstrom = 10^-10 m Hence,1 fermi / 1angstrom  = 10^-15/ 10^-10 = 10^-5 m

Q14. The number of significant figures in the distance of one light year , 9.4605 × 10¹⁵ m is

• Three
• Four
• Thirty
• Five

Solution

As the power of 10 is irrelevant in the determination of significant figures hence, the numbers of significant figures are 5.

Q15. Which of the quantity is dimensionless?

• Area
• Angle
• Force
• Work

Solution

Angle = length of Arc/ radius = L/L = 1 = [M⁰ L⁰ T⁰]

Q16. The most suitable instrument for measuring the size of an atom is.

• Screw gauge
• Vernier calliper
• Optical Microscope
• Electron microscope

Solution

Only electron microscope has resolution of 0.5-0.6 Angstrom which is less than the size of an atom.

Q17. Angstrom is the unit of

• Length
• Mass
• Time
• Light

Solution

A^o is the unit of length.

Q18. A vernier calipers is used for measuring lengths to an accuracy of:

• 10^-3 m
• 10^-2m
• 10^-1 m
• 10^-4 m

Solution

A vernier calipers is used for measuring lengths to an accuracy of 10^-4 m.

Q19. Which unit system is presently internationally accepted?

• cgs
• fps
• mks
• SI

Solution

International system of unit- SI is presently internationally accepted for measuring physical quantity.

Q20. A 5.2 g of a substance occupies 1.11 cm³. Its density to appropriate significant figure is:

• 4.68  
• 4.685  
• 4.7  
• 4.6845  

Solution

 There are 2 significant figures in measured mass whereas there are only 3 significant figures in measured volume. Hence density should be expressed to only 2 significant figures.        

Q21. The position of pen seems to be changed when you look at it through your left and right eye w.r.t to a fixed point on a wall. This effect is called ________ .

• Paradox
• Parallax
• Parallel method
• Popular method

Solution

Parallax effect arises due to the distance between our eyes.

Q22. Find the option with 5 significant figures

• 2.608 cm
• 0.02608 m
• 26.08 mm
• 2.6008 cm

Solution

26.008 have five significant figures where as 2.608 cm, 0.02608 m and 26.08 mm have four significant figures.

Q23. Find the odd one out.

• Length
• Mass
• Time
• Weight

Solution

Length, mass, and time are the base quantities where as weight is a derived quantity.

Q24. Three physical quantity having dimensions [M L^-1 T^-2] are

• Stress, pressure, coefficient of elasticity
• Stress, pressure, work
• Stress, pressure, density
• Stress, pressure, torque

Solution

Pressure = Force/Area = ML¹T^-2/ L² = [M L^-1 T^-2] Stress = Force/Area = ML¹T^-2/ L² = [M L^-1 T^-2] Coefficient of elasticity = Stress/strain = [M L^-1 T^-2]

Q25. The numbers of significant figures in 1.84 x10^-27 kg are:

• Three
• Four
• Thirty
• Five

Solution

As the power of 10 is irrelevant to the determination of significant figures hence, the numbers of significant figures are 3 (1, 8 and 4).

Q26. Random errors occur due to:

• imperfect design of instruments  
• parallax  
• fluctuations in temperature, supply,error in reading  
• incorrect rounding off  

Solution

They arise due to random and unpredictable fluctuations in experimental conditions (temperature, supply etc) and personal errors by the observer taking readings.    

Q27. Which of the following physical quantities has different dimensions?

• Work
• Energy
• Momentum
• Watt-hour

Solution

Momentum = Mass x Velocity = [M L T^-1]            

Q28. The base units for length, mass and time in MKS system are:

• cm, g, s
• cm, kg, s
• m, kg, s
• min, km, s

Solution

It is m, kg, s.

Q29. 1 unified atomic mass unit is equal to.

• 1/12 of the mass of an atom of carbon -12 isotope
• 1/13 of the mass of an atom of carbon-12 isotope
• 1/13 of the mass of an atom of carbon-13 isotope
• 1/14 of the mass of an atom of carbon-14 isotope

Solution

1 unified atomic mass unit is equal to 1/12 of the mass of carbon-12 [¹²C₆] isotope.

Q30. Which of the following physical quantity is dimensionless?

• Area
• Strain
• Stress
• Pressure