Heredity and Evolution — Science STD 10 — Question

What is solar constant? What is the value of solar constant?

State the law of combination of resistances in parallel.

A person is unable to see clearly a poster fixed on a distant wall. He however sees it clearly when standing at a
distance of about 2 m from the wall.
a. Draw ray diagram to show the formation of image by his eye lens when he is far away from the wall.
b. List two possible reasons of this defect of vision.
c. Draw ray diagram to show the correction of this defect using appropriate lens.

How were the positions of isotopes of an element decided in the modern periodic table?

Give two examples each of the metals that are good conductors and poor conductors of heat respectively.

An element X belongs to 3rd period and group 2 of the periodic table. State:

1. Number of valence electrons.
2. Valency.
3. Metal or non - metal.
4. Name of the element.

In what way are homologous organs evidence for evolution?

“To discard the household waste we should have two separate dust-bins, one for the biodegradable waste and the other for the non-biodegradable waste.” Justify this statement suggesting the proper way of disposal of these wastes.

Explain why, ethene decolourises bromine water whereas ethane does not.