List of top Science Questions

A person has a hearing range from 20 Hz to 20 kHz. What are the typical wavelengths of sound waves in air corresponding to these two frequencies? Take the speed of sound in air as 344 m s–1 .
What type of oxides are formed when non-metals combine with oxygen?
A truck starts from rest and rolls down a hill with a constant acceleration. It travels a distance of 400 m in 20 s. Find its acceleration. Find the force acting on it if its mass is 7 tonnes (Hint: 1 tonne = 1000 kg.)
Flash and thunder are produced simultaneously. But thunder is heard a few seconds after the flash is seen, why?
A batsman hits a cricket ball which then rolls on a level ground. After covering a short distance, the ball comes to rest. The ball slows to a stop because
How does the cork act as a protective tissue?
When a carpet is beaten with a stick, dust comes out of it, Explain.
What is the role of epidermis in plants?
Why do you fall in the forward direction when a moving bus brakes to a stop and fall backwards when it accelerates from rest?
A certain household has consumed \(250\) \(units\) of energy during a month. How much energy is this in joules?
Explain why some of the leaves may get detached from a tree if we vigorously shake its branch.
Does the transfer of energy take place when you push a huge rock with all your might and fail to move it? Where is the energy you spend going?
Name the regions in which parenchyma tissue is present.
What are the various energy transformations that occur when you are riding a bicycle?
In the following example, try to identify the number of times the velocity of the ball changes: “A football player kicks a football to another player of his team who kicks the football towards the goal. The goalkeeper of the opposite team collects the football and kicks it towards a player of his own team”. Also identify the agent supplying the force in each case.
The potential energy of a freely falling object decreases progressively. Does this violate the law of conservation of energy? Why?
A mass of 10 kg is at a point A on a table. It is moved to a point B. If the line joining A and B is horizontal, what is the work done on the object by the gravitational force? Explain your answer.
Identify the type of tissue in the following:
skin, bark of tree, bone, lining of kidney tubule, vascular bundle.
Certain force acting on a \(20\) \(kg\) mass changes its velocity from \(5\) \(m s^{–1}\) to \(2\) \(m s^{–1}\). Calculate the work done by the force.
A battery lights a bulb. Describe the energy changes involved in the process.
Which of the following has more inertia: (a) a rubber ball and a stone of the same size? (b) a bicycle and a train? (c) a five-rupees coin and a one-rupee coin?
An object thrown at a certain angle to the ground moves in a curved path and falls back to the ground. The initial and the final points of the path of the object lie on the same horizontal line. What is the work done by the force of gravity on the object?
Draw a labelled diagram of a neuron.
Differentiate between striated, unstriated and cardiac muscles on the basis of their structure and site/location in the body.
What is the specific function of the cardiac muscle?