GATE Questions

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Let the present ages of Kapil and Avanthi be K & A

Given difference in their ages = K - A = 9 years ...........(1)

After 7 years, K + 7 =  2(A + 7) ......(2)

K + 7 = 2A + 14

K - 2A = 7 ............(3)

K - A = 9 ....(1)

From (1) & (3),

-A = -2

=> A = 2 years

=> K = 9 + 2 = 11 years

Required, age of Kapil after 4 years = 11 + 4 = 15 years.

The mesosphere lies above the stratosphere and extends to an altitude of about 85 km. This is layer is often referred to as the cold layer, as the lowest readings in the atmosphere are found here.

Temperature decreases with height, reaching a minimum average value of -90 ºC at the top of the layer.

Sport played on horseback is called as Polo. It is the national sport of Iran.

The population is the smallest unit of living organisms that can undergo evolution.

We know that,  Speed = Distance/time

Let the speed of the train be = x kmph

           NORMAL SPEED                           SPEED 5 KMPH MORE

          Distance = 360 Km                         Distance =360
 
          speed    =  X Kmph                        Speed = (x+5)
 
            Time =360/X                              Time =360/(x+15)
          

For the same journey if the speed increased 10 kmph more it will take 1 hour less

Time with original speed - time with increased speed = 1

 => (360/x) - (360/x+10) =  1                               

 =>  (360(x+5)-360x)/x(x+5) =1

 =>   360X + 1800 -360X  = X(X+5)

  =>   X^2 + 5x - 1800 = 0

  X = 40 or -45

 X cannot be negetive value
                  

 X = 40 kmph.

From solving 1 and 2 we get,

1.

5a(a-3)-3(a-3) = 0

(5a-3)(a-3) = 0

a = 3 or 3/5

2. 

3b(b+2)-1(b+2) = 0

b = -2 or b = 1/3

Here when a = 3, a > b for b = -2 and b = 1/3

when a = 3/5. a > b for b = -2 and b = 1/3.

Hence, it is clear that a > b. 

Molecular compounds are those with covalent bonds between the elements and those elements are typically non metals.

Here in the given options, Ar is an element. NaI has an ionic bond. Hence, N2O4 has a covalent bond between the two non metals and is a molecular compound.

By trial and error method,

P=0, Q=9, R=0 satisfies the values.