Management of Natural Resources — Science STD 10 — Question

Explain why, the planets do not twinkle at night?

What are fossils? How do they act as an evidence for organic evolution?

Here are some results of solutions tested with universal indicator paper:

1. Sulphuric acid: Red
2. Metal polish: Dark blue
3. Washing-up liquid:
4. Yellow Milk of magnesia:
5. Light blue Oven cleaner:
6. Purple Car battery acid: Pink

Arrange the solutions in order of their increasing pH values (starting with the one with the lowest pH).

State the various steps involved in the process of photosynthesis.

The electronic configuration of an element ‘X’ is 2, 8, 8, 2. To which (a) period and (b) group of the modern periodic table does ‘X’ belong? State its valency. Justify your answer in each case.

1. A ray of white light breaks up into its components while passing through a glass prism. Draw a ray diagram to show the path of rays?
2. Mark the least deviated colour in your diagram?
3. Why do different coloured rays deviate differently in a prism?

Why is the leakage of LPG detected easily although it is odourless? State the steps to be taken in case its leakage is detected in the kitchen.

A magnesium ribbon is burnt in oxygen to give a white compound X accompanied by emission of light. If the burning ribbon is now placed in an atmosphere of nitrogen, it continues to burn and forms a compound Y.

1. Write the chemical formulae of X and Y.
2. Write a balanced chemical equation, when X is dissolved in water.

Explain why, aluminium is a highly reactive metal, still it is used to make utensils for cooking.

An object 20cm from a spherical mirror gives rise to a virtual image 15cm behind the mirror. Determine the magnification of the image and the type of mirror used.