Reproduction in Plants — Science STD 7 — Question

It was observed that when the distance between an object and a lens decreases, the size of the image increases. What is the nature of this lens? If you keep on decreasing the distance between the object and the lens, will you still able to obtain the image on the screen? Explain.

How does food move in opposite direction during vomiting?

Distinguish between the following. Ingestion and Egestion.

Magnesium ribbon burns in air and changes to white substance, i.e. magnesium oxide. When magnesium oxide dissolves in water, what type of change take place? Give reason in support of your answer. Express the change in the form of equation.

Draw a diagram to explain the different seasons on Earth.

It is established that an electric current through a metallic conductor produces a magnetic field around it. Is there a similar magnetic field produced around a thin beam of moving Justify your answer.

1. Alpha particles.
2. Neutrons.

Explain with the help of an example that the states of rest and motion are relative terms.

Have you even wondered why you get muscle cramps after heavy exercise?

Write short notes on:

1. In filtration.
2. Aquifer.

Explain humus and its importance.