Metals and Non-Metals — Science STD 10 — Question

Suggest how your irises help to protect the retinas of your eyes from damage by bright light.

Suggest a safe and efficient method for the disposal of biowastes and sewage materials. How is this method advantageous to us?

Write the molecular and structural formula of a cyclic hydrocarbon whose molecule contains 8 atoms of carbon.

Why does the sun appear reddish early in the morning? Will this phenomenon be observed by an observer on the moon? Justify your answer with a reason.
OR
Why does sun appear reddish at sunrise? Give reason.

Explain why, the current that makes the heater element very hot, only slightly warms the connecting wires leading to the heater.

List two observations on the basis of which it may be concluded that the given slide shows binary fission in Amoeba.

An element X from group 2 reacts with element Y from group 16 of the periodic table.

1. What is the formula of the compound formed?
2. What is the nature of bond in the compound formed?

Name the type of asexual reproduction in which two individuals are formed from a single parent and the parental identity is lost. Write the first step from where such a type of reproduction begins. Draw first two stages of this reproduction.

How is it that ionic compounds in the solid state do not conduct electricity but they do so when in molten state?

When the powder of a common metal is heated in an open china dish, its colour turns black. However, when hydrogen is passed over the hot black substance so formed, it regains its original colour. Based on the above information answer the following questions:

1. What type of chemical reaction takes place in each of the two given steps?
2. Name the metal initially taken in the powder form. Write balanced chemical equations for both reactions.