English Medium कक्षा १० - CBSE Question Bank Solutions

Explain with the help of a labelled ray diagram, why a pencil partly immersed in water appears to be bent at the water surface. State whether the bending of pencil will increase or decrease if water is replaced by another liquid which is optically more dense than water. Give reason for your answer.

Light travelling from a denser medium to a rarer medium along a normal to the boundary:

(a) is refracted towards the normal
(b) is refracted away from the normal
(c) goes along the boundary
(d) is not refracted

When a ray of light travelling in glass enters into water obliquely:

(a) it is refracted towards the normal
(b) it is not refracted at all
(c) it goes along the normal
(d) it is refracted away from the normal

A ray of light passes from a medium X to another medium Y. No refraction of light occurs if the ray of light hits the boundary of medium Y at an angle of:

(a) 0°
(b) 45°
(c) 90°
(d) 120°

A vertical ray of light strikes the horizontal surface of some water: 

 What is the angle of incidence?

A vertical ray of light strikes the horizontal surface of some water: 

What is the angle of refraction? 

How does the light have to enter the glass: 

 to produce a large amount of bending?

How does the light have to enter the glass: 

 for no refraction to happen? 

Fill in the following blank with suitable word:

 Ethene and ethyne are examples of ..... hydrocarbons.

 Fill in the following blank with suitable word:

Carbon compounds have usually ... melting points and boiling points because they are ...... in nature.

What is the difference between two consecutive homologues:
(1) in terms of molecular mass?
(2) in terms of number and kind of atoms per molecule?

Give the molecular formula of one homologue of the following:

C₃H₆

Give the molecular formula of one homologue of each of the following:

C₂H₆

Write the names and formulae for the first three members of the homologous series for chloroalkanes.

Define a homologous series. Give the name and structural formula of one homologue of the following:
CH₃OH

Write the molecular formula of the third member of the homologous series of carbon compounds with general formula C_nHO_2n+1OH.

What is a homologous series? Explain with an example.

The molecular formula of an organic compound is C₁₈H₃₆. Name its homologous series.