After viewing different slides, a student draws following diagrams. Select the one which depicts binary fission in amoeba:

A student prepared an aqueous solution of CuSO₄ in beaker X and an aqueous solution of FeSO₄ in beaker Y. He then dropped some iron pieces in beaker X and some zinc pieces in beaker Y. After about 10 hours he observed that the solutions in X and Y respectively appear:

• blue and green

• colorless and pale green

• colourless and light blue

• colourless and light blue

The sky appears dark instead of blue to an astronaut. State its reason.

Name the functional group present in each of the following compounds:

(i) HCOOH

(ii) C₂H₅CHO

A student takes Na₂CO₃ powder in a test tube and pours some drops of acetic acid over it. He observes:

• no reaction in the test tube

• colourless gas with pungent smell

• bubbles of a colourless and odourless gas

• bubbles of a colourless and odourless gas

A student adds 4 mL of acetic acid to a test tube containing 4 mL of distilled water. He then shakes the test tube and leaves it to settle. After about 10 minutes he observes:

• a layer of water over the layer of acetic acid 

• a layer of acetic acid over the layer of water

• a precipitate settling at the bottom of the test tube

• a precipitate settling at the bottom of the test tube

State the modern periodic law for classification of elements. How many (i) groups and (ii) periods are there in the modern periodic table?

Name two decomposers operating in our ecosystem.

Which of the following observations is true about dilute solution of acetic acid?

• It smells like vinegar and turns red litmus blue 

• It smells like onion and turns blue litmus red

• It smells like orange and turns red litmus blue

• It smells like orange and turns red litmus blue

Depletion of ozone in the ozone layer is a cause for our worry. Why?