List of top Science Questions asked in CBSE X

The autotrophic mode of nutrition requires

The xylem in plants are responsible for

The kidneys in human beings are a part of the system for

How many 176 Ω resistors (in parallel) are required to carry 5 A on a 220 V line?
When a 12 V battery is connected across an unknown resistor, there is a current of 2.5 mA in the circuit. Find the value of the resistance of the resistor.
The human eye can focus objects at different distances by adjusting the focal length of the eye lens. This is due to
A student has difficulty reading the blackboard while sitting in the last row. What could be the defect the child is suffering from? How can it be corrected?
What is the far point and near point of the human eye with normal vision?
How is a voltmeter connected in the circuit to measure the potential difference between two points?

Explain the mechanism of the cleaning action of soaps.

Two conducting wires of the same material and of equal lengths and equal diameters are first connected in series and then parallel in a circuit across the same potential difference. The ratio of heat produced in series and parallel combinations would be –

Give a test that can be used to differentiate between saturated and unsaturated hydrocarbons

Which of the following hydrocarbons undergo addition reactions: C2H6 , C3H8 , C3H6 , C2H2 and CH4 .

What change will you observe if you test soap with litmus paper (red and blue)?

Explain the formation of scum when hard water is treated with soap.

Why are carbon and its compounds used as fuels for most applications?

Why does micelle formation take place when soap is added to water? Will a micelle be formed in other solvents such as ethanol also?

Which of the following terms does not represent electrical power in a circuit?
A piece of wire of resistance R is cut into five equal parts. These parts are then connected in parallel. If the equivalent resistance of this combination is R′, then the ratio \(\frac {R}{R^′}\) is –

How can ethanol and ethanoic acid be differentiated on the basis of their physical and chemical properties?

What is an homologous series? Explain with an example.

Draw the electron dot structures for 
(a) ethanoic acid. 
(b) H2S. 
(c) propanone. 
(d) F2

Explain the nature of the covalent bond using the bond formation in CH3Cl.

While cooking, if the bottom of the vessel is getting blackened on the outside, it means that

Ethane, with the molecular formula C2H6 has