P-2 Animal Classification — Science STD 10 — Question

How many bonds have to be there in between the carbon atoms in ethyne so as to satisfy their tetra valency?

Ciliary muscles of human eye can contract or relax. How does it help in the normal functioning
of the eye?

From the standpoint of atomic structure, what determines which element will be the first and which the last in a period of the periodic table?

DEFINE : Applied microbiology.

Metals X and Y can be recovered from the anode mud left behind after the electrolytic refining of copper metal. The coins made of metal X look new even after several years of use but the coins made of metal Y lose their shine gradually and get blackened soon. When metal X is alloyed with a small amount of metal Y, it becomes hard and hence suitable for making ornaments. What are metals X and Y ? Also state the colour of metal X.

Why does aluminium not corrode right through?

“Respiration is a vital function of the body”. Justify this statement.

Surabhi from Std. X uses spectacles. The power of the lenses in her spectacles is 0.5 D. Answer the following questions from the given information: (March 2019)
(i) Identify the type of lenses used in her spectacles.
(ii) Identify the defect of vision Surabhi is suffering from.
(iii) Find the focal length of the lenses used in her spectacles.

When a pm of height 3 cm is fixed at 10 cm from a convex lens, the height or the virtual image formed is 12 cm. Find the focal length of the lens.

The 'rocket' is a type of fire cracker used in Diwali.
(a) Name the launcher.
(b) Name the law on which its working is based.