GATE Questions

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An Indian boy has won the world’s largest pre-college science competition in the US in the environmental engineering category for his project on biodegradation of pesticides. Prashant Ranganathan, a 12th grader from Jamshedpur, alongwith over 20 high school students from various parts of India, participated in the Intel International Science and Engineering Fair.

The stability of the ions is determined by the energy of the lone pairs. Carbon has the least effective nuclear charge (Zeff) and so the lone pair on the CH3− ion has the highest energy, making it the least stable ion and so the strongest base. The Zeff increases as we move across the period until we get to fluorine which has the greatest Zeff and so its lone pairs have the lowest energy, making F− the least basic ion.

In order of decreasing basicity they are ranked LiCH3 > LiNH2 > LiOH > LiF. We are dealing with the ions F−, OH−, NH2− and CH3− and so the factor which influences their basicity is the stability of the ion compared to its conjugate acid.

Given (3 Men + 4 Women + 6 Children) -----> 9 days

But W = 2M and C = M/2

Now, convert Men and Children into Women by

$$\begin{gathered} 3W2 + 4W + 6W4 \\ => 32 + 4 + 32 = 7 Women \end{gathered}$$ 

Therefore, 7 women alone can complete this work in 9 days.

Let the amount collected be 'A'
Then, from the given conditions,
A x 110/100 x 90/100 = 7920
A x 0.99 = 7920
A = 7920/0.99
=> 8000

Let Priyatham's age = x

Then, Vishal's age = 2x; Raghu's age = x/2; Veeru's age = 4x ; Karthik's age = x/4

So, the descending order of ages is :

Veeru > Vishal > Priyatham > Raghu > Karthik

Therefore,  Karthik is the youngest.

Sound intensity is measured in decibels(db). Sound pollution above 120 db becomes more hazardous and have adverse affects on human life. 

As the distance travelled is constant, the time taken is inversely proportional to speed.

Let 'u' be the speed of the current and 'v' be the speed of the boat.

Speed of the boat downstream = v + u & upstream = v - u

=> v+u/v-u = 30/20 => v/u = 5 => v = 5u

=> v + u = 6u = 10/20/60 miles/hr

=> 6u = 30 m/h

=> u = 5 m/h

Microwaves are high-frequency signals in the 300 MHz to 300 GHz range. This is in contrast to radio signals, which are typically broadcast in all directions. Radio signals operate in the 3 Hz to 300 MHz range.

Microwave signals are used for both satellite and ground-based communications.