List of top Science Questions

List two constituents of Central Nervous System (CNS). How are these components protected from injuries?
What is photosynthesis? Name the organelle and the organs in which photosynthesis takes place. Where does the oxygen liberated come from during this process? What happens to the carbohydrates which are not immediately used by the plant?
List any two methods by which the solid wastes generated in urban areas can be safely disposed off.
Assertion (A) : Each human trait is influenced by both paternal and maternal DNA.
Reason (R) : As compared to the father, the mother contributes more amount of genetic material to the child.

Find the magnification of the image formed by a spherical mirror from the following data :
$u = -20$ cm,  $f = -15$ cm.

“In human beings, the sex of a newborn child depends on the father and not the mother.” Justify this statement with the help of a flow diagram.
In the electrolysis of water, if the mass of the gas collected at the anode is $m_a$ and the mass of the gas collected at the cathode is $m_c$, the value of $\frac{m_c}{m_a}$ is :

The resistance of a wire does not depend on its :

Explain by giving one example each:
(1) Unisexual flowers
(2) Bisexual flowers

Absolute refractive indices of water and glass are $\frac{4}{3}$ and $\frac{3}{2}$ respectively. In which one of the two media is the speed of light more?

The absolute refractive indices of water and glass are $\frac{4}{3}$ and $\frac{3}{2}$ respectively. If the speed of light in glass is $2 \times 10^8$ m/s, find the speed of light in (i) water and (ii) vacuum.
“A ray of light incident on a rectangular glass slab immersed in any medium emerges parallel to itself.” Draw a labelled ray diagram to justify this statement.
Define the term absolute refractive index of a medium.
If a ray of light enters obliquely from glass to water, will it bend towards the normal or away from the normal?
Why is aluminium used to join railway tracks or the cracked machine parts of ‘iron’? Write a balanced chemical equation for the reaction which occurs.
How is the brain protected from shocks and injuries?
Write the main functions of (i) sensory neuron and (ii) motor neuron in a reflex arc.
Which part of the brain is involved in activities like (i) picking a pencil and (ii) vomiting? State whether these actions are voluntary or involuntary.
How does the central nervous system communicate with other parts of the body to carry out various activities? Name two components of this system.
Define water of crystallisation.
Name the parts in the human female reproductive system where the following functions take place:
(1) Maturation of eggs
(2) Fusion of the egg and the sperm
(3) Implantation of the zygote

Name the labelled parts A, B, C and D in the diagram given below.

The commercial unit of electric energy is commonly known as ‘unit’. Write its actual name and establish the relationship between this unit and the SI unit of energy.
Where is iron placed in the reactivity series of metals? Write the form/forms in which its ores are found in nature.
Define trophic levels. At which trophic level do we find (i) secondary and (ii) tertiary consumers in a food chain? What will happen if all the organisms of a trophic level die? Give reasons to justify your answer.