Tips and Tricks of The Day


Record Limit : 

    2020-Feb-20
Ex: A ball P is dropped vertically and another ball Q is thrown horizontally with the same velocities from the same height and at the same time. If air resistance is neglected, then
A) Ball P reaches the ground first
B) Ball Q reaches the ground first
C) Both reach the ground at the same time
D) The respective masses of the two balls will decide the time
Explanation: Vertical component of velocities of both the balls are same and equal to zero. So t = √2h/g
    2020-Feb-19
Ex: In a surface tension experiment with a capillary tube water rises upto 0.1 m. If the same experiment is repeated on an artificial satellite, which is revolving around the earth, water will rise in the capillary tube upto a height of:  
A) 0.1 m    
B) 0.2 m
C) 0.98 m
D) Full length of the capillary tube
Explanation: In the satellite, the weight of the liquid column is zero. So the liquid will rise up to the top of the tube.
    2020-Feb-18
Ex: A positively charged ball hangs from a silk thread. We put a positive test charge q0at a point and measure F/q0, then it can be predicted that the electric field strength E:
A) > F/q0
B) = F/q0
C) < F/q0          
D) Cannot be estimated
Explanation: Because of the presence of positive test charge q0 in front of positively charged ball, charge on the ball will be redistributed, less charge on the front half surface and more charge on the back half surface. As a result of this net force F between ball and point charge will decrease i.e. actual electric field will be greater than F/q0.
    2020-Feb-17
Ex: The substance which is mixed with the ore for removal of impurities is termed as:
A) Slag
B) Gangue
C) Flux
D) Catalyst
Explanation: Flux is added during smelting it combines with infusible gangue present in the ore to form a fusible mass known as slag. 
Flux + Gangue → Slag
    2020-Feb-14
Ex: The oxidation state of cobalt in the complex compound [Co(NH3)6]Cl3 is:
A) + 3
B) + 6
C) + 5
D) + 2
Explanation: [Co(NH3)6]Cl3 → [Co(NH3)6]3+ +3Cl x + 6(0) = +3 ⇒ x = +3
    2020-Feb-13
Ex: In a surface tension experiment with a capillary tube water rises upto 0.1 m. If the same experiment is repeated on an artificial satellite, which is revolving around the earth, water will rise in the capillary tube upto a height of
A) 0.1 m    
B) 0.2 m
C) 0.98 m
D) Full length of the capillary tube
Explanation: In the satellite, the weight of the liquid column is zero. So the liquid will rise up to the top of the tube.
    2020-Feb-12
Ex: The electrons, identified by quantum numbers n and l (i) n = 4, l= 1, (ii) n = 4, l= 0, (iii) n = 3, l= 2, and (iv) n =3, l = 1 can be placed in order of increasing energy, from the lowest to highest, as
A) (iv) < (ii) < (iii) < (i)
B) (ii) < (iv) < (i) < (iii)
C) (i) < (iii) < (ii) < (iv)
D) (iii) < (i) < (iv) < (ii)
Explanation: 
The two guiding rules to arrange the various orbitals in the increasing energy are:          
(i) Energy of an orbital increases with increase in the value of n+1           
(ii) of orbitals having the same value of n+1, the orbital with lower value of n has lower energy.           
Thus for the given orbitals, we have           
(i) n+1=4+1=5    (ii) n+1=4+0=4       (iii) n+1=3+2=5       (iv) n+1=3+1=4
Hence, the order of increasing energy is     (iv) < (ii) < (iii) < (i)
    2020-Feb-11
Ex: The aqueous solution of FeCl3 is acidic due to:
A) Acidic impurities              
B) Ionisation
C) Hydrolysis          
D) Dissociation
Explanation: FeCl3 is a salt of weak base (Fe(OH)3)and strong acid (HCl).
    2020-Feb-10
Ex: In a capillary tube experiment, a vertical 30 cm long capillary tube is dipped in water. The water rises up to a height of 10cm due to capillary action. If this experiment is conducted in a freely falling elevator, the length of the water column becomes:
A) 10 cm
B) 20 cm
C) 30 cm 
D) Zero
Explanation: The length of the water column will be equal to full length of capillary tube.    
    2020-Feb-07
Ex: When a ferromagnetic material is heated to temperature above its Curie temperature, the material:
A) Is permanently magnetized
B) Remains ferromagnetic
C) Behaves like a diamagnetic material
D) Behaves like a paramagnetic material
Explanation: When a ferromagnetic material in heated above its curie temperature then it behaves like paramagnetic material.