Our Environment — Science STD 10 — Question

Why homologous series of carbon compounds are so called? Write chemical formula of two consecutive members of a homologous series and state the part of these compounds that determines their (i) physical properties, and (ii) chemical properties.

Explain briefly, how rainwater harvesting is done from open spaces around the buildings in city areas.

If the image formed by a lens for all positions of the object placed in front of it is always virtual, erect and diminished, state the type of the lens. Draw a ray diagram in support of your answer. If the numerical value of focal length of such a lens is 20cm, find its power in new cartesian sign conventions.

1. Name the following:

1. Thread like non-reproductive structures present in Rhizopus.
2. 'Blobs' that develop at the tips of the non-reproductive threads in Rhizopus

2. Explain how these structures protect themselves and what is the function of the structures released from the 'blobs' in Rhizopus.

If a potential difference of 10V causes a current of 2A to flow for 1 minute, how much energy is transferred?

Explain with the help of labelled ray-diagram, the defect of vision called hypermetropia, and how it is corrected by a lens.

A magnifying lens has a focal length of 100mm. An object whose size is 16mm is placed at some distance from the lens so that an image is formed at a distance of 25cm in front of the lens.

1. What is the distance between the object and the lens?
2. Where should the object be placed if the image is to form at infinity?

A solution of potassium chloride when mixed with silver nitrate solution, an insoluble white substance is formed. Write the chemical reaction involved and also mention the type of the chemical reaction?

Compare the nervous system and endocrine system (hormonal system) for control and coordination in humans.