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

Where is iron placed in the reactivity series of metals? Write the form/forms in which its ores are found in nature.
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.
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.
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.

What is Tyndall effect? Give two examples where this phenomenon is observed. Give reason to explain this phenomenon.
What is meant by residual volume of air in the lungs?
Write any two ways by which plants obtain carbon dioxide. What causes the opening and closing of the stomata?
With the help of a labelled circuit diagram, illustrate the pattern of the magnetic field lines of the magnetic field produced around a straight current carrying conductor. Explain how, with the help of right-hand thumb rule, we can determine and mark the direction of magnetic field lines due to a current.
An organic compound ‘X’ when reacts with sodium liberates hydrogen. The same compound ‘X’ when heated at 443 K in the presence of concentrated sulphuric acid gives an unsaturated hydrocarbon.
(i) Identify ‘X’.
Why are carbon compounds exceptionally stable?

Draw a labelled ray diagram for the image formation by a concave mirror when an object is placed between its centre of curvature and focus.

What will happen if an electric oven of rating 3 kW; 220 V is operated in a domestic electric circuit (220 V) that has a current rating of 10 A? Give reason to justify your answer.
State any one advantage of using cloth bags over plastic bags.
Name the glands which add their secretions to the sperms. List two functions of these secretions.
Assertion (A) : A rainbow is an artificial spectrum of white light appearing in the sky after a rain shower.
Reason (R) : The water droplets act like small prisms.
(a) A metal ‘A’ reacts violently with cold water and the gas evolved catches fire. Another metal ‘B’ when dipped in water starts floating. The metal ‘C’ does not react either with cold or hot water, but reacts with steam. The metal ‘D’ does not react with water at all. Identify the metals ‘A’, ‘B’, ‘C’ and ‘D’.
When two compounds namely sodium chloride and calcium chloride are heated directly, one by one on the flame of a burner, they impart different colours to the flame.
Name the colour imparted by (1) sodium chloride and (2) calcium chloride.
Are these compounds soluble in organic solvents such as kerosene or petrol? Justify your answer.
Assertion (A) : A hormone called abscisic acid inhibits growth in plants.
Reason (R) : The role of auxins is opposite to that of abscisic acid in plants.
When an object is placed beyond 2F of a convex lens, the nature of the image formed is :
When a narrow beam of white light passes through a glass prism it splits into its component colours. This phenomenon is called :
Assertion (A) : In the reaction, Na$_2$SO$_4$ + BaCl$_2$ $\longrightarrow$ BaSO$_4$ + 2NaCl, sodium chloride is precipitated.
Reason (R) : When an aqueous solution is added to another aqueous solution, an insoluble substance is formed, which is called precipitate.
A material used for making heating elements of electrical heating devices should have :
The shape of magnetic field lines produced (i) inside a solenoid (ii) around a straight conductor, both carrying current of the same magnitude are, respectively :