English Medium इयत्ता १० - CBSE Important Questions for Science

Explain the term absolute refractive index of a medium and write an expression to relate it with the speed of light in vacuum.

What is a solenoid?

Out of the two-reuse and recycle-which, in your opinion, is better to practise? Give reason.

List two problems that arise due to the use of detergents instead of soaps.

Write the name and structural formula of the compound obtained when ethanol is heated at 443 K with excess of conc. H₂SO₄. Also write chemical equation for the reaction stating the role of conc. H₂SO₄ in it.

List two functions ovary of human female reproductive system.

Describe placenta structure.

Write two examples of sexually transmitted diseases caused by virus.

Write two examples of sexually transmitted diseases caused by bacteri.

Explain how the transmission of virus and bacteria diseases be prevented?

Mention the types of mirrors used as (i) rear view mirrors, (ii) shaving mirrors. List two reasons to justify your answers in each case.

1. Determine the speed of light in diamond if the refractive index of diamond with respect to vacuum is 2.42. Speed of light in vacuum is 3 × 10⁸ m/s. 
2. Refractive indices of glass, water and carbon disulphide are 1.5, 1.33 and 1.62 respectively. If a ray of light is incident in these media at the same angle (say θ), then write the increasing order of the angle of refraction in these media. 
3. (A) The speed of light in glass is 2 × 10⁸ m/s and is water is 2.25 × 10⁸ m/s.
   (a) Which one of the two optically denser and why?
   (b) A ray of light is incident normally at the water glass interface when it enters a thick glass container filled with water. What will happen to the path of the ray after entering the glass? Give reason. 
   OR
   (B) The absolute refractive indices of glass and water are 4/3 and 3/2, respectively. If the speed of light in glass is 2 × 10⁸ m/s, calculate the speed of light in (i) vacuum (ii) water.

Define the term dispersion of white light.

Name and state the rule of determine the direction of force experienced by a current carrying straight conductor placed in a uniform magnetic field which is perpendicular to it. 

State the reason to explain why covalent compounds "are bad conductors of electricity".

Write the name and general formula of a chain of hydrocarbons in which an addition reaction with hydrogen is possible. State the essential condition for an addition reaction. Stating this condition, write a chemical equation giving the name of the reactant and the product of the reaction.

For preparing soap in the laboratory we require an oil and a base. Which of the following combinations of an oil and a base would be best suited for the preparation of soap?

(a) Castor oil and calcium hydroxide

(b) Turpentine oil and sodium hydroxide

(c) Castor oil and sodium hydroxide

(d) Mustard oil and calcium hydroxide

Write the molecular formula of two consecutive members of homologous series of aldehydes. State which part of these compounds determines their

1. physical and 
2. chemical properties

State the reason to explain why covalent compounds "are bad conductors of electricity".

Complete the following chemical equations : C₂H₅OH + Na →