Who was the first Chief Election Commissioner of India?

Solution
Archimedes Principle states that upward buoyant force exerted on a body immersed in a fluid is equal to the weight of the fluid the body displaces.
Iron is extracted from

Solution
Magnetic keepers are pieces of soft iron that are placed across the poles of a bar magnet or a horseshoe magnet. They help prevent the loss of magnetism
A ‘Bit’ refers to

Solution
Phenotype refers to a set of observable characterstics of an individual or group resulting from the interaction of its genotype with its environment. Gene pool refers to the stock of different genes in an interbreeding population.
A light year is a unit of

Solution
CaseinLactose proteinsugar pair is present in milk. Normal bovine milk contains 3035 grams of protein per litre of which about 80 per cent is arranged in casein micelles.
Persons suffering from myopia are advised to use

Solution
Lead storage battery was invented by French physicist Gaston Plante in 1859. In the discharged state both the positive and negative plates become lead sulphate and the electrolyte loses much of its dissolved sulphuric acid and becomes primarily water.
Which of the following is not a computer network?
The vitamin necessary for coagulation of blood is
Breeding and management of bee is known as
The best conductor of electricity among the following is
The minimum number of geostationary satellite needed for uninterrupted global coverage is
The average of seven numbers is 18. If one of the numbers is 17 and if it is replaced by 31, then the average becomes

Solution
Difference = 31  17 = 14
∴ Required average =18 +^{14}⁄_{7}= 20
In how many years will a sum of money double itself at 12% per annum?

Solution
If the principal be Rs 100 then SI = Rs 100.
∴ Time =\(\frac{SI\times 100}{Pr incipal \times Rate}\)
\(=\frac{100 \times 100}{100 \times 12}=\frac{25}{3}years\)
= 8 years 4 months
An article marked Rs 800 is offered at Rs 736 in the off season, The rate of discount offered is

Solution
Discount = Rs (800  736) = Rs. 64.
∴ Discount per cent = ^{64}⁄_{800} × 100 = 8%
The simplest value of sin^{2}5° + sin^{2}10° + sin^{2}15°+… + sin^{2}85°+ sin^{2}90° is

Solution
5, 1O, 15 ..... 90 is an arithmetic sequence whose
first term = 5 and common difference = 5
If the number of terms be n, then
t_{n} = a + (n  1)d⇒ 90 = 5 + (n  1) x 5
⇒ 85 = ( n  1) x 5
⇒ n  1 = 17 ⇔ n = 18
(Note : Divide 90 by 5 to get number of terms here)
∴ Expression = (sin^{2} 5° + sin^{2} 85°) + (sin^{2}10° + sin^{2} 80°)................... 8 terms + sin^{2} 45° + sin^{2}90°= (sin^{2}5° + cos^{2} 5°) + (sin^{2}10°+ cos^{2} 10°) +................... 8 terms +\(\left ( \frac{1}{\sqrt{2}} \right )^{2}+1\)
\(=8+\frac{1}{2}+1=9\frac{1}{2}\)
[∴ sin (90°θ) = cosθ ; sin^{2} 8 + cos^{2}θ 8 = 1]
A parallelopiped whose sides are in ratio 2:4:8 have the same volume as a cube. The ratio of their surface area is

Solution
Let the sides of the parallelopiped be 2x, 4x and 8x units respectively and the edge of cube be y units.
Now, according to the question,
∴ 2x× 4x× 8x= y^{3}
⇒8 ×8×^{3}=y^{3}
Taking cube roots,
⇒ 4x = Y....(i)
Surface area of parallelopiped
= 2 (2x × 4x + 4x × 8x + 8x × 2x)
= 2 (8x^{2} + 32x^{2} + 16x^{2})
= 112x^{2} sq units
Surface area of cube = 6y^{2} sq units∴ Required ratio =\(\frac{112x^{2}}{6y^{2}}=\frac{112x^{2}}{6×16x^{2}}\)
\(=\frac{7}{6}=7:6\)
Directions : Select the one which is different from the other three responses.
Directions : Select the one which is different from the other three responses.
Directions : Select the related letter number from the given alternatives.
Dog: Rabies :: Mosquito: ?
Directions : Select the related letter number from the given alternatives.
VXZ : JLN :: GIK?
Directions : Select the related letter number from the given alternatives.
6 : 35 :: 7 : ?

Solution
As, 6 × 5 = 30;
30 + 5 = 35
Similarly, 7 × 6 = 42;
42 + 6 = 48
Or, As, (6)^{2}  1 = 35
Similarly, (7)^{2}  1 = 48