1. A student obtained a sharp image of a candle flame placed at the distant end of the laboratory table on a screen using a concave mirror to determine its focal length. The teacher suggested him to focus a distant building, about 1 km away from the laboratory, for getting more correct value of the focal length. In order to focus the distant building on the same screen, the student should slightly move the: 

• mirror away from the screen
• screen away from the mirror
• screen towards the mirror
• screen towards the mirror

• erect and laterally inverted
• erect and diminished
• inverted and diminished
• inverted and diminished

Select from the following the best experimental setup for tracing the path of a ray of light passing through a rectangular glass slab.

• P

• Q

• R

• R

Study the following figure in which a student has marked the angle of incidence (<i), angle of refrcation (< r), angle of emergence (< e), angle of prism ( < A) and the angle of deviation (<D). The corrected angles are: 

Which of the following sets of materials can be used for conducting a saponification reaction for the preparation of soap?

• Ca(OH)₂ and neem oil 

• NaOH and neem oil

• NaOH and mineral oil. 

• NaOH and mineral oil. 

A student takes four test tubes marked P, Q, R and S of 25 mL capacity and fills 10 mL of distilled water in each. He dissolves one spoon full of four different salts in each as − KCl in P, NaCl in Q, CaCl₂ in R and MgCl₂ in S . He then adds 2 ml of a sample of soap solution to each of the above test tubes. On shaking the contents of each of the test tubes, he is likely to observe a good amount of lather (Foam) in the test tubes marked. 

• P and Q

• R and S

• P, Q and R

• P, Q and R

Consider the following comments about saponification reactions; 
I. Heat is evolves in these reactions.
II. For quick precipitation of soap, sodium chloride is added to the reaction mixtures. 
III. Saponification reactions are a special kind of neutralization reactions.
IV. Soaps are basic salts of long-chain fatty acids

• I, II and III

• II, III and IV

• I, II and IV

• I, II and IV

A student has to perform the experiment " To identify the different parts of an embryo of an embryo of a dicot seed. "

• Pea, gram, wheat

• Red kidney bean, maize, gram 

• Maize, wheat, red kidney bean

• Maize, wheat, red kidney bean

Which of the following is a correct set of homologous organs?

• Forelimbs of a frog, bird and lizard

• Spine of cactus and thorn of Bougainvillea

• Wings of bat and wings butterfly

• Wings of bat and wings butterfly

Write the next homologue of each of the following:
i) C₂H₄
ii) C₄H₆