English Medium Class 10 - CBSE Question Bank Solutions

The molecular formula of a homologue of butane is:
(a) C₄H₈
(b) C₃H₆
(c) C₄H₆
(d) C₃H₈

The number of carbon atoms present in the molecule of fifth member of the homologous series of alkynes is:

(a) four
(b) five
(c) six
(d) seven

The molecular formula of the third member of the homologous series of ketones is:
(a) C₄H₈O
(b) C₃H₆O
(c) C₅H₁₀O
(d) C₆H₁₂O

An organic compound having the molecular formula C₃H₆O can exist in the form of two isomers A and B having different functional groups. The isomer A is a liquid which is used as a solvent for nail polish. The isomer B is also a liquid. An aqueous solution of one of the lower homologues of B is used for preserving biological specimens in the laboratory
(a) What is compound A?
(b) Write the electron-dot structure of A.
(c) What is compound B?
(d) Write the electron-dot structure of B.
(e) Name the lower homologue of compound B  which is used in preserving biological specimens.

A colourless organic liquid X of molecular formula C₂H₄O₂ turns blue litmus to red. Another colourless organic liquid Y of molecular formula C₃H₆O has no action on any litmus but it is used as a nail polish remover. A yet another colourless organic liquid Z of molecular formula C₂H₆O has also no action on litmus but it is used in tincture of iodine.

(a) Name the liquid X. To which homologous series does it belong? Give the name of another member of this homologous series.
(b) Name the liquid Y. To which homologous series does it belong? Write the name of another member of this homologous series.
(c) Can you name an organic compound having the same molecular formula as liquid Y but which belongs to a different homologous series? What is this homologous series?
(d) Name the liquid Z. To which homologous series does it belong? Write the name of another member of this homologous series.

Write the name and molecular formula of the first member of the homologous series of alkynes.

Why homologous series of carbon compounds are so called? Write chemical formula of two consecutive members of a homologous series and state the part of these compounds that determines their (i) physical properties, and (ii) chemical properties.

Study the different conclusions drawn by students of a class on the basis of observations of preserved/available specimens of plants and animals.

I. Potato and sweet potato are analogous organs in plants.

II. Wings of insects and wings of birds are homologous organs in animals.

III. Wings of insects and wings of bats are analogous organs in animals.

IV. Thorns of citrus and tendrils of cucurbita are analogous organs in plants.

The correct conclusions are:

(A) I, and II

(B) II and IV

(C) I and III

(D) III and IV

Define homologous series of organic compounds. List its two characteristics. Write the name and formula of the first member of the series of alkenes.

Distinguish between homologous organs and analogous organs. In which category would you place wings of a bird and wings of a bat? Justify your answer giving a suitable reason.

Define the principal focus of a concave mirror.

Light enters from air to glass having refractive index 1.50. What is the speed of light in the glass? The speed of light in vacuum is 3 × 10⁸ m s⁻¹.

What is atmospheric reflection? Explain with the help of a labelled diagram that the position of a star as seen by us is not its true position. 

What is haemoglobin? State the consequences of deficiency of haemoglobin in our bodies. 

List four characteristics of the image formed by a concave lens of focal length 20 cm when the object is placed at a distance of 40 cm from its optical centre. 

The size of image of an object by a convex lens of focal length 20 cm is observed to be reduced to  `1/3` rd of its size . Find the distance of the object from the optical centre of the lens . 

List in proper sequence the steps of the experiment for determining the approximate focal length of a given concave mirror by obtaining the image of a distant object.

A real image is formed by the light rays after reflection or refraction when they:

1. actually meet or intersect with each other.
2. actually converge at a point.
3. appear to meet when they are produced in the backward direction.
4. appear to diverge from a point.

Which of the above statements are correct?

Write the mathematical expression for Joule’s law of heating.