In the preparation of soap, sodium chloride causes:

(i) Which property of concave mirror is utilized for using them as shaving mirrors?

(ii) Light passes through a rectangular glass slab and through a triangular glass prism. Using proper ray diagram, explain in what way does the direction of the two emergent beams differs with respect to the incident beam of light.

(iii) A concave lens has a focal length of 50 cm Calculate its power.

(i) Rohit claims to have obtained an image twice the size of object with a concave lens. Is he correct? Give reason for your answer.

(ii) Where should an object be placed in case of a convex lens to form an image of same size as of the object? Show with the help of ray diagram the position and the nature of the image formed.

(iii) With the help of ray diagram, illustrate the change in position, nature and size of the image formed if the convex lens in case of (ii) is replaced by concave lens of same focal length.

Vishakha carried out saponification reaction in the lab and she gave following comments as:

(i) Soap is salt of fatty acid.

(ii) Heat is absorbed in this reaction.

(iii) Reaction mixture is basic in nature

(iv) These are neutralization reaction

The correct statements are:

Select from the following salts which may be used to prepare hard water required for the experiment.

A. CaSO₄

B. Na₂SO₄

C. CaCl₂

D. K₂SO₄

E. NaHCO₃

F. MgCl₂