Heredity and Evolution — Science STD 10 — Question

Write the number of periods the modern periodic table has. How do the valency and metallic character of elements vary on moving from left to right in a period? How do the valency and atomic size of elements vary down a group?

Describe an activity to show that the colours of white light splinted by a glass prism can be recombined to get white light by another identical glass prism. AIso draw ray diagram to show the recombination of the spectrum of white light.

What is meant by dispersion of white light? Describe the formation of rainbow in the sky with the help of a diagram.

State the energy conversion taking place in the solar cell panel. For what purpose, solar cell panel is used? State its two main advantages.

What are the two negative impacts of a hydro power plant on the ecosystem?

The three elements A, B and C with similar properties have atomic masses X, Y and Z respectively. The mass of Y is approximately equal to the average mass of X and Z. What is such an arrangement of elements called as? Give one example of such a set of elements.

State the cause of dispersion of white light passing through a glass prism. How did Newton show that white light of sun contains seven colours using two identical glass prisms. Draw a ray diagram to show the path of light when two identical glass prisms are arranged together in inverted position with respect to each other and a narrow beam of white light is allowed to fall obliquely on one of the focus of the first prism.

Describe the working of a hydrogen bomb.

What is a seed? What are the parts of a seed? Explain with the help of a labelled diagram.