P-1 Periodic Classification of Element — Science STD 10 — Question

Write the equations for the reactions of:

1. Magnesium with dilute hydrochloric acid.
2. Aluminium with dilute hydrochloric acid.
3. Zinc with dilute hydrochloric acid.
4. Iron with dilute hydrochloric acid.

Name the products formed in each case. Also indicate the physical states of all the substances involved.

If a concave mirror has a focal length of 10cm, find the two positions where an object can be placed to give, in each case, an image twice the height of the object.

Every household produces a lot of material A daily. In one of the methods of disposal B, material A is burned at a very high temperature of about 1000°C in a structure called C. During this process, the organic matter present is removed as D and E whereas F is left behind (which can be dumped in a landfill site).

1. What is material A?
2. Name the method of disposal B.
3. What is structure C known as?
4. What are (i) D (ii) E, and (iii) F?
5. This method is especially suitable for the disposal of materials produced by certain institutions. Name such institutions.

Depending on electronic configuration the properties of elements vary in different periods. Explain why?

Explain the theory of evolution and mention the proof supporting it.

A food chain occurring in the sea which provides food for many people can be written as:
phytoplankton → zooplankton → X → Y

1. Name one phytoplankton.
2. Name two zooplanktons.
3. What could be X?
4. Name the organism which Y could be.
5. Which organism in the above food chain is a (i) primary consumer, and (ii) tertiary consumer?

Write the names of all the major endocrine glands present in the human body. Which of these glands also function as exocrine glands?

When a female child is born, her ovaries already contain thousands of immature eggs (or ova) contained in immature structures A. On maturing, A bursts open and an egg shoots out of the ovary in a process called B. The process B starts in the females at puberty and occurs again and again after a time period x. Before every occurrence of process B, the inner lining of uterus becomes thick and soft with lots of blood vessels in it. When the egg cell gets fertilised by a sperm, then an event C occurs in the life of mature human female which lasts for time period y leading to the birth of baby. If, however, the egg cell released by the ovary does not get a sperm to fuse with, then the thick and soft inner lining of uterus breaks down and comes out of the female's body in an event called D. The occurrence of event D is controlled by chemical substances E.

1. What are A?
2. What is process B?
3. What is the time period x?
4. Name the event C.
5. How much is the time period y?
6. What is the name of process D?
7. Name the chemical substances E.

The mass and weight of an object on earth are 5 kg and 49 N respectively. What will be their values on the moon? Assume that the acceleration due to gravity on the moon is 1/6th of that on the earth

What does a soda-acid type fire extinguisher contain? How does it work?
Explain the working of a soda- acid fire extinguisher with the help of a labelled diagram.