Electricity — Science STD 10 — Question

What are esters? How are they prepared? List two uses of esters.

A non-metal gains electrons to form anions. What do you mean by this statement?

With the help of a flow chart explain in brief how the sex of a newborn is genetically determined in human beings. Which of the two parents, the mother or the father, is responsible for determination of the sex of a child?

Two lenses have powers of (i) +2D and (ii) -4D. What is the nature and focal length of each lens?

What is meant by ‘systolic pressure’ and ‘diastolic pressure’? What are their normal values?

Sudha finds out that the sharp image of the window pane of her science laboratory is formed at a distance of 15cm from the lens. She now tries to focus the building visible to her outside the window instead of the window pane without disturbing the lens. In which direction will she move the screen to obtain a sharp image of the building? What is the approximate focal length of this lens?

State the 10% law, associated with the flow of energy in trophic levels of organisms.

Draw a labelled ray diagram to show how a ray of light passes through a parallel sided glass block:

1. If it hits the glass block at 90° (that is, perpendicular to the glass block).
2. If it hits the glass block at an angle other than 90° (that is, obliquely to the glass block).

Give one example each of a salt which gives an aqueous solution having:

1. pH less than 7
2. pH equal to 7
3. pH more than 7