Sources of Energy — Science STD 10 — Question

Students were asked to observe the permanent slides showing different stages of budding in yeast under high power of a microscope.

1. Which adjustment screw (coarse/ fine) were you asked to move to focus the slides?
2. Draw three diagrams in correct sequence showing budding in yeast.

A bulb is rated as 250V; 0.4A. Find its : (i) power, and (ii) resistance.

An existing population of birds was suddenly wiped out from an area. Give a suitable reason for the same.

What is the difference between the cuttings method and grafting method for the artificial propagation of plants?

While studying the dependence of potential difference (V) across a resistor on the current (I) passing through it, in order to determine the resistance of the resistor, a student took 5 readings for different values of current and plotted a graph between V and I. He got a straight line graph passing through the origin. What does the straight line signify? Write the method of determining the resistance of the resister using this graph.

Draw diagram to represent the action of a concave mirror on a beam of parallel light rays. Mark on this diagram principal axis, focus F, centre of curvature C, pole P and focal length ƒ, of the concave mirror.

Why is white phosphorus kept immersed under water?

How would you distinguish experimentally between an alcohol and a carboxylic acid on the basis of a chemical property?

Give the relationship between the wavelength of light and its angle of deviation, when it is passed through a prism.

What do you understand by the “resistivity” of a substance?