List of top Science Questions asked in CBSE Class X

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.

List any two methods by which the solid wastes generated in urban areas can be safely disposed off.

Name the glands which add their secretions to the sperms. List two functions of these secretions.

“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.

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’.

Are these compounds soluble in organic solvents such as kerosene or petrol? Justify your answer.

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.

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 :

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 :

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.

Which one of the following metals is malleable and a poor conductor of electricity ?

Which one of the following molecules is produced initially when glucose breaks down in the cytoplasm of a cell in aerobic as well as anaerobic respiration ?

As compared to daytime, the amount of carbon dioxide released by the plants during night is more because :

The organism in which an outgrowth on the parent body develops into a new individual is :

2 g of yellow sulphur powder is burnt in a china dish and the fumes are collected in a test tube. Water is added in the test tube and the solution is tested separately with blue and red litmus paper. The correct option is :

In a cross between pure tall pea plants (TT) and pure dwarf pea plants (tt) the offsprings of F$_1$ generation were all tall. When F$_1$ generation was self-crossed, the gene combinations of the offsprings of F$_2$ generation will be :

Consider the following substances : (i) Acidified K$_2$Cr$_2$O$_7$
(ii) Alkaline KMnO$_4$
(iii) Oxygen
(iv) Hydrogen
Out of these, the commonly used oxidising agents are :

Select from the following compounds which is not a base :

Explain the following in terms of gain or loss of oxygen with two examples each. 
(a) Oxidation
(b) Reduction