Archives

The present age of Ravi and Menu are in the ratio 5:7. After 4 years their age will be in the ratio 3:4. Find their ages.

Let the present age of Ravi = 5y years Let the present age of Meenu = 7y years According to condition: 5y +4 / 7y+4 =3/4 = 20y +16= 21y +12... View Article

A bus decreases its speed from 80 kilometres per hour to 60 km per hour in 5 seconds, find the acceleration of the bus.

Answer: Acceleration is defined as the rate of change of velocity with respect to time. A body’s acceleration is the final result of all the... View Article

To account for the atomic mass of nitrogen as 14.0067 what should be the ratio of N15 and N14 atoms in natural nitrogen?

Let xl= the fraction of N-15. Then, 1−x= the fraction of N-14 and 14.003 07(1−x)+15.001x=14.0067 14.003 07 - 14.003... View Article

A solid cylinder has a radius of 2 cm and a length of 7 cm. It has a density of 3.1 g/cm 3. What is the mass of the cylinder?

Mass of the cylinder can be calculated by: m = volume x density m = pie* r^2 *l * d m = 3.14* (2)^2 * 7* 3.1 m = 272.552 gram... View Article

Liquefaction of gases is the process by which substances in their gaseous state are converted to the liquid state. Explain

Liquefaction of gases is the physical conversion of a gas into a liquid state. When pressure on a gas is increased, its molecules closer... View Article

The temperature on the moon varies between 110 degrees Celsius to -170 degrees Celsius. What is the possible reason for this?

The moon is at the same distance from the sun as the earth is but there is very cold and hot temperature variations. The main reason behind this... View Article

Who formed the Jacobin Club? What measures had he taken to remove discrimination in French society and form a French Republic?

The Jacobin Club was formed by Maximilian Robespierre. One of the influential political clubs that formed by Maximilian Robespierre during the... View Article

In a cell current flows from positive to negative, then where is the loss of current when it again reach to the cell or battery

The direction of an electric current is by convention the direction in which a positive charge would move. Thus, the current in the external... View Article

The sum of the areas of two squares is 468 m^2. If the difference of their perimeters is 24 m, find the sides of the two squares

Let the sides of the first and second square be X and Y. We know that area of square= side x side = side 2 Area of the first square = (X)²... View Article

In class, there are 15 boys and 10 girls. How many ways a teacher can select 1 boy and 1 girl to represent the class at a seminar?

There are 15 boys and 10 girls as per the given details, Therefore total strength is 25 The no of ways to select 3 members out of 25 is 25 c 3 =... View Article

Write the density of Silver, Nickel, Lanthanum, Neptunium, Tin and Proctatinium and arrange them from the least dense to the densest.

Silver - 10.49 Nickel - 8.94 Lanthanum - 6.15 Neptunium - 20.2 Tin - 7.26 Proctatinium - 15.4 The ascending order of the densities of these... View Article

Although the water is transparent, and there are water droplets present in the fog then why are we not able to see things during fog?

Fog shows up when water vapor, or water in its gaseous form, condenses. During condensation, molecules of water vapor combine to make tiny liquid... View Article

During day time sky is seen in blue colour due to scattering of light. Light reaching in a room is also scattered light. But no blue colour is seen. Why

Scattering of light is the phenomenon in which light rays get deviated from its straight path on striking an obstacle like dust or gas molecules,... View Article

A 50W bulb is in series with a room heater and the combination is connected across the mains. To get max. heater output, the 50W bulb should be replaced by

Heating output of heater =I2R = v2R1/(R1+R2)2 If R2 is decreased the current (i.e v/R1+ R2) is increased So, the heating output will be higher... View Article

an athlete completes one round of a circular track of diameter 200m in 40s what will be the distance covered and the displacement at the end of 2min 20s

Answer: Distance and displacement are two terms that appear to be identical but have quite different meanings and definitions. The term distance... View Article

Why does nothing happen to us when we drink water, as our stomach contains HCl and when water is added to conc. acids, a highly exothermic reaction takes place?

The hydrochloric acid in the stomach is already quite dilute; its pH is, in fact, less than 1.5 so that at the extreme maximum there is only 0.03... View Article

If it takes 31536000 seconds for the earth to complete one revolution, how many hours will it take to complete 100 revolutions? Express the answer in standard form

One day is one revolution around itself. 1 day is 24 hours, or 1440 min, or 86,400 sec. One year is one revolution around the sun. 1 year is... View Article

A chair and a table cost 1800 rupees. If by selling the table at a profit of 15% and a chair at a loss 10% total profit of 6% is made .what is the cost price of a chair

Given Cost of chair and table together = Rs 1800 6% profit is made by selling the table at a profit of 15% and the chair at a loss of 10%. To... View Article

A person walks with velocity V in a straight line forming an angle theta with the plane of a plane mirror. Find the velocity V relative with which he approaches his image

If V be the velocity of approach at an angle θ, then velocity along the perpendicular direction will be Vsinθ. The image will also... View Article

In the game of cricket, the stump falls down when a ball strikes it this the example of which force? a] frictional force b] gravitational force c]muscular force c] none of these

The contact forces represent the result of physical contact between two objects, one by which force is exerted and the other on which force is... View Article