1 P – Block Elements
What is the n factor or valancy factor of ozone during the change 2O3? → 3O2?? 1) 2 2) 4 3) 6 4) 8
SOLUTION
2O3 → 3O2 2mole O3 ≡ 3mole O2=3×4eq.O2 ≡12 eq.O2 ∴1 moleO3=6eq.O2
2 Electromagnetic Waves
A plane electromagnetic wave of frequency 20 MHz travels through a space along x direction. If the electric field vector at a certain point in space is 6 V m-1, what is the magnetic field vector at that point?
1) 2 x 10-8 T 2) (1 / 2) x 10-8 T 3) 2T 4) (1 / 2)T
3 Work Power Energy
How many kilowatts are required to raise a weight of 25 N a distance of 8.0 m in 2.5 minutes? 1) 1.33 E - 3 kW 2) 2.63 E - 2 kW 3) 1.86 E 2 kW 4) 3.35 E -5 kW
4 Titrations
In permanganometric titrations, the end point is :
1) yellow colour
2) pink colour
3) red colour
4) colourless
During permanganate tirtrations such as titration of potassium permanganate with oxalic acid, oxalic acid solution is in a conical flask and potassium permanganate solution is in the burette. As the end point is reached, the solution changes colour to pink as potassium permanganate has intense purple colour. Even a slight excess of it will give pink colour.
5 Work Power Energy
A crane is used to lift 10000 kg of coal from a mine 100 m deep. If the time taken by the crane is 1 hr, then find the power of the crane, assuming the efficiency of the crane to be 80%. (g=9.8 m/s2) :
1) 2567 watt 2) 2403 watt 3) 3403 watt 4) 3761 watt
SOLUTION We are given that the mass(m) of the crane = 10000 kg and displacement(s) = 100m
Thus, we have Work done = F×s
= (10000×9.8)×100
= 98×105 joule
We also know that power is work done in the given time or
Thus, we have power of the crane (P) to be 3403 watts.
6 Polymers
Which of the following is fully fluorinated polymer?
1) PVC 2) Thiokol 3) Teflon 4) Neoprene
Teflon is polymer of CF2 = CF2 .
7 Sequences and Series
If n geometric means between a and b be G1,G2,G3,.......,Gn, and a geometric mean be G , then the true relation is 1) G1.G2 …….Gn = G 2) G1.G2 …….Gn = G1/n 3) G1.G2 …….Gn = Gn 4) G1.G2 …….Gn = G2/n
Here G = (ab)1/2 and G = ar1 , G2 = ar2 , ……. G = arn
Therefore G1,G2,G3,.......,Gn
= anr 1+2+…+n = anrn(n+1)/2
8 Limits and Continuity
If f(x) = , then f(x) is 1) Continuous on [-1, 1] and differentiable on (-1, 1) 2) Continuous on [-1, 1] and differentiable on (-1, 0) ∪ (0, 1) 3) Continuous and differentiable on [-1, 1] 4) None
Solution
9 Principle of Mathematical Induction
x (xn – 1 - n an – 1 ) + an (n – 1) is divisible by (x – a)2 for 1) n > 1 2) n > 2 3) n ∈ N 4) n > 2, n ∈ N
For n = 1, the given expression is zero and hence the statement is true for n = 1.and by induction statement is true for each n
10 Aldehydes Ketones and Carboxylic Acids
In nucleophilic addition reactions the reactivity of carbonyl compound follows order 1) H2C=O >R2C=O > Ar2C = O > RCHO > ArCHO 2) H2C=O > RCHO > ArCHO > Ar2C = O 3) Ar2C = O > R2C=O > ArCHO > H2C=O 4) ArCHO > Ar2C = O > RCHO > R2C=O > H2C=O
Aldehydes are more reactive than ketones twards nucleophilic addition reaction. Aromatic aldehydes and ketones are less reactive than corresponding aliphatic aldehydes and ketones.
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