Human Eye and Colourful World — Science STD 10 — Question

The depth of a bucket filled with water seems to be less than its actual depth. Name the phenomenon responsible for this?

Give the law of combination of resistances in series.

With the help of examples, describe how metal oxides differ from non-metal oxides.

Name one element in which corrosion is not proved to be wasteful.

What will you do if you see a person coming in contact with a live wire?

Can the organisms of any trophic level be removed without causing any damage to the ecosystem? Will the impact of removing all the organisms in a trophic level be different for different trophic levels?

Give the names and formulae of two strong bases and two weak bases.

The following table gives the refractive indices of a few media,

	1	2	3	4	5
Medium:	Water	Crown glass	Rock salt	Ruby	Diamond
Refractive index:	1.33	1.52	1.54	1.71	2.42

Use this table to give an example of:

1. A medium pair so that light speeds up when it goes from one of these medium to another.
2. A medium pair so that light slows down when it goes from one of these medium to another.

Write the molecular formula of:

1. An alkane.
2. An alkene.
3. An alkyne, each having 20 carbon atoms?

When a solution is added to vanilla extract, then the characteristic smell of vanilla cannot be detected. State whether the given solution is an acid or a base.