English Medium कक्षा १० - CBSE Important Questions for Science

Why are metals good conductors of electricity whereas glass is a bad conductor of electricity? Give reason?

Why are alloys commonly used in electrical heating devices? Give reason.

State Fleming’s left hand rule.

What is meant by homologous series of carbon compounds?

State the reason why carbon can neither form C⁴⁺ cations nor C⁴⁻ anions but forms covalent compounds.

On what factors does the resistance of a conductor depend?

State significance of pollination.

Write one main difference between asexual and sexual mode of reproduction. Which species is likely to have comparatively better chances of survival – the one reproducing asexually or the one reproducing sexually? Give reason to justify your answer.

Define the power of a lens.

What is a solenoid?

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. 

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.

Give one example of a unisexual flower.

Mention the changes a flower undergoes after fertilisation.

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

Define the term dispersion of white light.

State the rule to determine the direction of a magnetic field produced around a straight conductor-carrying current.

What are alloys?

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