A student puts a drop of the reaction mixture of a saponification reaction first on a blue litmus paper and then on red litmus paper. He may observe that: 

• There is no change in the blue litmus paper and the red litmus paper turns white.

• There is no change in the red litmus paper and the blue litmus paper turns red.

• There is no change in the blue litmus paper and the red litmus paper turns blue.

• There is no change in the blue litmus paper and the red litmus paper turns blue.

For preparing soap in the laboratory, we require an oil and a base. which of the following combination of an oil and base would be best suited for preparation of soap.

• Castor oil and calcium hydroxide

• Turpentine oil and sodium hydroxide

• Castor oil and sodium hydroxide

• Castor oil and sodium hydroxide

In the neighbourhood of your school, hard water required for an experiment is not available. Select from the following groups of salts available in your school a group each member of which if dissolved in distilled water, will make it hard:

• Sodium chloride, calcium chloride

• Potassium chloride, sodium chloride

• Sodium chloride Magnesium chloride

• Sodium chloride Magnesium chloride

4.

A student while observing an embryo of a pea seed in the laboratory listed various parts of the embryo as given below:

Testa, Tegmen, Radicle, Plumule, Micropyle, Cotyledon.

On examining the list the teacher remarked that only three parts are correct. Select three correct parts from the above list.

• Testa, Radicle, Cotyledon

• Tegmen, Radicle, Micropyle

• Cotyledon,Plumule, Testa

• Cotyledon,Plumule, Testa

If you are asked to select a group of two vegetables, out of the following, having homologous structures which one would you select?

• Carrot and radish

• Potato and sweet potato

• Potato and tomato

• Potato and tomato

To determine the approximate value of the focal length of a given concave mirror, you focus the image of a distant object formed by the mirror on a screen. The image obtained on the screen, as compared to the object is always:

• Laterally inverted and diminished

• Inverted and diminished

• Erect and diminished

• Erect and diminished

Suppose you have focused on a screen the image of candle flame placed at the farthest end of the laboratory table using a convex lens. If your teacher suggests you to focus the parallel rays of the sun, reaching your laboratory table, on the same screen, what you are expected to do is to move the:

• lens slightly towards the screen

• lens slightly towards the screen

• lens slightly towards the sun

• lens slightly towards the sun

In your laboratory you trace the path of light rays through a glass slab for different values of angle of incidence (i) and in each case measure the values of the corresponding angle of refraction (r) and angle of emergence (e). On the basis of your observations your correct conclusion is:

• i is more than r, but nearly equal to e
• i is less than r, but nearly equal to e
• i is more than e, but nearly equal to r
• i is more than e, but nearly equal to r

In the following ray diagram the correctly marked angle are:

Write the name and structure of an alcohol with three carbon atoms in its molecules.