Management of Natural Resources — Science STD 10 — Question

What are the three types of methods used for birth control (or regulating child birth)? Give one example of each type.

What happens when

1. Planaria gets cut into two pieces?
2. A mature spirogyra filament attains considerable length?
3. On maturation sporangia burst?

How does the resistance of a conductor depend on:

1. Length of the conductor?
2. Area of cross-section of the conductor?
3. Temperature of the conductor?

Consider two elements 'A' (Atomic number 17) and 'B' (Atomic number 19):

1. Write the positions of these elements in the modern periodic table giving justification.
2. Write the formula of the compound formed when 'A' combines with 'B.'
3. Draw the electron dot structure of the compound and state the nature of the bond formed between the two elements.

State the safety measures in using electricity.

If a potential difference of 10V causes a current of 2A to flow for 1 minute, how much energy is transferred?

Rays from the sun converge at a point 15cm in front of a concave mirror. Where an object should be placed, so that its image formed is equal to the size of the object?

Trace the sequence of events which occur when a bright light is focused on your eyes.

Explain why the planets do not twinkle.