List of top Science Questions asked in CBSE Class X, CBSE Compartment X

The pattern of magnetic field due to a current carrying wire depends upon the shape made by that wire. Justify.
Assertion : In human beings, the respiratory pigment is haemoglobin present in red blood cells.
Reason (R) : Haemoglobin has a very high affinity for carbon dioxide.
Assertion (A): Reflex actions do not involve thinking.
Reason (R): Most reflex actions are controlled by the spinal cord.
Draw the ray diagram for the image formation by a lens which shows a magnification of +2.
In human beings, the implantation of fertilised egg takes place in which part of female reproductive system?
How is a universal indicator obtained? How is the wide range of pH of solution tested by it?
Mention the gland and the hormone secreted by it in scary situation in human beings.
State two differences between the act of chewing food and salivation on sight of food.
The formula of functional group for aldehyde is :
(a) Study the given electric circuit in which 2 A electric current is flowing between points X and Y.

(i) Using the battery, key, voltmeter and ammeter in this given electric circuit, redraw a circuit diagram in which 2 \(\Omega\) and 4 \(\Omega\) resistors are connected between X and Y in parallel combination.
(ii) Circuit drawn by you, in which resistors are connected in parallel combination, calculate the electric current flowing through 4 \(\Omega\) resistor.
Given below is a pyramid showing various trophic levels in an ecosystem:
(a) From the organisms listed below, identify which one is to be placed at which trophic level:
Deer, Grass, Lion, Snake, Rabbit
(b) Discuss the reason why primary consumers will have more energy as compared to secondary consumers?
(c) Why is the base of the pyramid broad?
Briefly mention the steps in double-circulation through human heart.
(a) Why is bile juice considered to be very important for digestion, even though it doesn't contain any digestive enzymes?
(b) Name some substances present in initial filtrate and subsequently selectively reabsorbed in the tubules of nephron.
What is the function of diaphragm in human respiratory system ? Where is it present in human body ?
Which structure in a leaf is mainly responsible for gaseous exchange?

The reasons for excessive generation of wastes are:
 (i) Use and throw policy. 
(ii) Increased availability of packaged food. 
(iii) Increased construction wastes. 
(iv) Non-sorting of dry and wet wastes

Why does an electric bulb become dim when an electric heater in parallel circuit is switched ON?
Assertion : The needle of a magnetic compass kept in strong external magnetic field, always aligns itself in north-south direction on the earth. Reason (R): Behaviour of the needle of a compass is same as that of a freely suspended bar magnet.

The given figure shows image formation by a lens. Analyse the figure and answer the following questions : 


What is the type of lens used for image formation in the given ray diagram ? 
If the real image is formed at a distance of \( 30 \text{ cm} \) from the lens and the size of image is twice the size of the object, then where was the object placed ? 
 

Imagine that you are sitting in a chamber with your back to one wall. An electron beam, moving horizontally towards the front wall from the back wall, is deflected by a strong magnetic field to your right side. Find the direction of the magnetic field.
Draw a neat diagram to show germination of pollen on the female reproductive part of the flower. Name and label only the following parts:
(a) The part that receives the pollen grain.
(b) The structure that carries the male germ cell to reach the female germ cell.
Identify the correct statement for spirogyra, leishmania and hydra
What happens when ethanol is heated with alkaline KMnO$_4$? Write chemical equation involved.
Giving reason explain what type of materials are used in fuse wires.
Distinguish between overloading and short-circuiting of a circuit.