Metals and Non-Metals — Science STD 10 — Question

How are general growth and sexual maturation different from each other?

What is a balanced chemical equation? Why should chemical equations be balanced?

What happens when calcium reacts with water? Write the chemical equation of the reaction of calcium with water.

Explain why, a human zygote is more likely to grow into an adult than a frog zygote.

Why does distilled water not conduct electricity, whereas rain water does?

Draw ray diagrams each showing:
Myopic eye.

What type of lens is shown in the diagram on the right? What will happen to the parallel rays of light? Show by completing the ray diagram.

A student focuses the image of a candle flame, placed at about 2 m from a convex lens of focal length 10 cm, on a screen. After that he moves gradually the flame towards the lens and each time focuses its image on the screen.

1. In which direction does he move the lens to focus the flame on the screen?
2. What happens to the size of the image of the flame formed on the screen?
3. What difference is seen in the intensity (brightness) of the image of the flame on the screen?
4. What is seen on the screen when the flame is very close (at about 5 cm) to the lens?

How would you distinguish experimentally between an alcohol and a carboxylic acid on the basis of a chemical property?