MCQs and tricks for competition exam.

  Cube root  If we remember the cube of numbers from 1 to 10, then we will be able to find the cube root of numbers up to 100000 very easy i.e. in few seconds.  The cube of the numbers from 1 to 10 is:-  1³ = 1  2³ = 8  3³ = 27  4³ = 64  5³ = 125  6³ = 216  7³ = 343  8³ = 512  9³ = 729  10³ = 1000  Q. 1.  Find the cube root of 97,336.  Solution:- Unit digit -6  Hence the unit digit of the required number is 6.  ( 216= 6³)  Now, 97  -----  (distinguish 336)  The perfect cube number below 97 is 64 which is the cube of 4. Hence tens digit = 4   Cube root of 97,336 = 46  Q.2.  Find the cube root of 2744 .  Solution:  2  744  unit digit = 4  cube number below 2 = 1 Cube root of 1 = 1  ∴  1  4  Ans: 14  If the unit digit of the number is 8 then the unit digit of its cube root will be 2. And if the unit digit of the numbe...

  1.  During the electrolysis of Cu₂SO₄ (Copper Sulphate)  substance deposited at the anode:-  A. Hydrogen  B. copper  C. Oxygen  D. sulphate  Ans: C. Oxygen  2. Which of the following solution does not conduct electricity:-  A. Urea  B. Benzene  C. sugar  D. all three  Ans: D. All three  3.The material on which the electroplating is to be done, that material is made of:-  A. Anode  B. cathode  Ans: B. Cathode  4. On electrolysis of sodium chloride, Na⁺ ions will be deposited in:-  A. cathode  B. anode  Ans: A. Cathode  5. Electric current flows in an electrolytic material:-  A. By electrons.  B. by protons.  C. by neutrons.  D. by ions.  Ans: D. By ions.  6. The total charge  of 1 mole of electrons is equal to:-  A. 96000 faraday  B. 69600Faraday  C. 96500 Faraday  D. 96700 Faraday  Ans: C. 96500 Faraday  7. ...

 • Top MCQ Q&A Notes related to pH which is very important for various competitive exams.  1. What is the pH value :-  A. negative log value of oxygen ion concentration.  B. negative log value of OH-  ion concentration.  C. Negative log value of hydrogen ion concentration.  D. negative log value of nitrogen ion concentration.  Ans: C. Negative log value of hydrogen ion concentration.  2. The range of pH value is :-  A. 0 to 14  B. 0 to 7  C. 0 to 10  D.  7 to 14  Ans : A. 0 to 14   3. The pH  value of an acid is :-  A. 0  B. 7  C. more than 7   D. less than 7  Ans: D. Less than 7  4. The pH  value of alkali is :-  A.  14  B.  more than 7  C. less than 7  D.  0  Ans : B. More than 7  5. What is the pH value of neutral solution :-  A. 7  B. 14  C. 0   D. 1  Ans : A. 7  6. How much ch...

  1) 1 kwH  is equal to how many joules:-  A. 1000 joules  B. 3.6 × 10⁵ joules  C. 3.6×10⁶ joules  D. 3.6×10³ joules  Ans.C.  3.6 × 10⁶  joules   2) The value of 1HP(horse power)  is equal to:-  A. 500 watts  B. 240 watts  C. 340 watts  D. 746 watts  Ans.4.  746  Watts  3) An object situated at a height of h m is stored in:-  1. potential energy  2. Kinetic Energy  3. Gravitational Energy  4.Magnetic Energy  Ans.  1.  potential energy  4) The SI  unit of power is :-  1. Watt  2. joule  3. Tesla  4. Ohms  Ans.1.  Watt  5) The SI  unit of work is :-  1. Watts  2. joule  3.Tesla  4. Ohms  Ans.2.  joule  6) When an object of mass m is raised to a height h , the potential energy stored in it will be:-  1. ½mv²  2. mh  3. mgh  4. mv  Ans.3. mgh   7) Th...

  Work and energy:- Physics numerical problems for competition exam preparation  Q.1.  A 10 kg object is raised to a height of 6 m. How much work is done in lifting the object?    A) 425 joules  B) 378 joules  C) 500 joules  D) 588 joules  ANSWER= D)588 joules  Explain:-  m= 10kg, h = 6 m  Hence mgh = 10×6×9.8  = 588 joules  Work done in raising an object to a height h = At ​​h height, potential energy of the object  Q.2.  The mass of an object is 10 kg.  Find the work done in increasing its velocity from 5 m/s to 10 m/s.    A) 375 joules  B) 300 joules  C) 510 joules  D) 275 joules  ANSWER= A)375 joules  Explain:- work = change in kinetic energy  ={ (½)×10×10²}-{(½)×10×5²  = 500-125  = 375 joules  Q.3.  A force of 20N is applied on an object placed on a flat surface.  If the object is displaced by a distance of 2 m, how much wor...

 Physics numerical :- Force and Momentum  Q.1 .  A force of 12 N on an object produces an acceleration of 4 m/s.  How much force is needed to produce an acceleration of 10 m/s?  A) 30N  B) 12N  C) 10N  D) 20N  ANSWER= A ) 30N  Explain:-  F = ma  m = F/a  m = 12/4  m =3 kg  Therefore, force for an acceleration of 10 m/s² = ma  = 3×10  = 30N ans.  Q.2.  The momentum of an object is 20 kgm/s.  How much force is needed to stop it in 4 seconds :-  A) 4N  B) 12N  C) 10N  D) 5N  ANSWER= D) 5N  Explain:- From the formula of impulse,  force × time = change in momentum  Now, initial momentum = 20 kgm/s  Final momentum = 0 kgm/s (momentum also becomes zero when velocity is zero)  Change in momentum = 20 - 0  = 20 kgm/s  Therefore, F× 4=20  F = 20/4  = 5N ans.  Q.3.  An 80 g bullet is fired from a 20 kg gun with a velocit...

  Sound and wave numerical problems for various competition exam.  Q.1.  If the wavelength of the wave is 5 m and the time period is 2 seconds, then how much time will the wave take to cover a distance of 50 m?    A) 25 seconds  B) 20 seconds  C) 15 seconds  D) 10 seconds  ANSWER= B) 20 seconds  Explanation:- The time period is called the time taken to complete 1 oscillation.  The wavelength is distance by 1 oscillation.  Hence, time taken to cover a distance of 5 meters = 2 seconds  Time taken to cover a distance of 1 meter = 2/5 second  Time taken to cover a distance of 50 meters = (2/5)×50  =2×10  = 20 seconds  Q.2.  If the frequency is 2 Hz, what will be the wavelength of the wave?     A) 1.5 m  B) 0.5 m  C) 2.5 m  D) 3.5 m  ANSWER= D) 0.5 m  Explain:-  = 1÷2  =0.5m  {Formula :- = 1/n}  Q.3.  If the frequency is 30 Hz, find t...

  Physics numerical in English:- chapter- light reflection and refraction  Q.1.  If the focal length of the lens is 10 cm, then what will be the power of the lens?    A) 10D  B) 0.1D  C) 5D  D) 20D  ANSWER= A) 10D.  Explain:- 1. If the focal length is given in cm, then the power of the lens will be :-  100/f  2.  If the focus distance is given in m, then the power of the lens will be :-  1/f  Here it is given in cm.  Hence the power of the lens = 100/f  = 100/10  = 10D  Q.2.  What will be the focal length of the lens whose power is +2 D :-  A) 10cm  B) 5cm  C) 50 cm  D) 20cm  ANSWER= C) 50cm.  Explain:- Here the focus distance is given in cm.  Hence, the power of the lens = 100/f  2 = 100/f  f =100/2  = 50 cm  Q.3.  The magnifying power of an astronomical telescope is 10.  If the focal length of the objective lens is 1 ...

  Physics numerical :- chapter- Gravitational force  Q.1.  What will be the weight of an object weighing 15 kgf on the moon? :-  A) 12 N  B) 15 N  C) 25.83 N N  D) 22.11 N  ANSWER= C) 25.83 N  Explanation:- To convert kgf to newton, it is multiplied by 9.8.  Therefore,  15kgf = 15×9.8  =155.0N  The weight of the object on the Moon is ⅙ times the weight of the object on the Earth.  Therefore, the weight of a 15kgf object on the moon would be 155÷6 = 25.83 N.  Q.2.  The value of g is 9.3 at a height of 100 m, then at what depth from the surface of the earth will the value of g become 9.3 m/s²?:-  A) 200 m  B) 100 m  C) 400 m  D) 900 m  ANSWER= A) 200 m  Explain:- The value of g at h height and g at d depth has the following relation:-  d =2h  so d=2×100  =200 m  Q.3.  What is the weight of 1 kg object? :-  A) 98 N  B) 1000 N  C) 1 N  D)...

 Physics numerical in Hindi:- chapter - Electricity(Electric Current)  Q.1.  The resistance of a wire is 40Ω.  If the length of the wire is doubled, find the resistance of the new wire.  A) 140  B) 60  C) 80  D) 160Ω   ANSWER= D) 160Ω  Explain:-  1. Trick solution :-  (n)² × R  =(2)²× 40  = 160Ω  Q. 2. The resistance of a wire is 40Ω.  The length of that wire has been increased to 5 times without any change in volume.  Find the resistance of the new wire.  A) 1000Ω  B) 600  C) 800  D) 1600Ω   ANSWER= A) 1000Ω  Explain:-  1. Trick solution :-  (n)² × R  = (5)² × 40  = 1000Ω  Q. 3. Resistance of a wire is RΩ.  If the length of this wire is stretched n times.  The resistance of the new wire will be :-  A) nR  B) n²R  C) R/ n  D) n /R   ANSWER= B) n²R  Explain:-    Q.4.  The resistance of a wire is ...

  Best trick to remember atomic weight number in Hindi  Here is a very good way to remember atomic mass number so that you can remember atomic mass number very easily   Atomic Mass Number :- The mass number of an atom is the sum total of the number of protons and the number of neutrons.  Z = p + n  The atomic mass number is expressed in amu(atomic mass unit) .   To prepare for various exams, you must read these posts of ours:-  biology gk set-1  V.V.I gk Question :- Reflection and Refraction of Light  pH value gk questions  Geography Set-1(100 Questions)  In this method you must remember the value of atomic number of elements. Here is how to calculate mass number up to 40.  This method fails when the mass number is more than 40.  Generally questions up to mass number 40 are asked in the examinations.  Mass numbers greater than that will have to be crammed or another method is adopted.  • How to easily remember th...