Life Processes — Science STD 10 — Question

Power of a lamp is 60 W. Find the energy in joules consumed by it in 1s.

Describe the process of respiration in fish.

A convex lens of focal length 6cm is held 4cm from a newspaper which has print 0.5cm high. By calculation, determine the size and nature of the image produced.

An object 2cm tall is placed on the axis of a convex lens of focal length 5cm at a distance of 10m from the optical centre of the lens. Find the nature, position and size of the image formed. Which case of image formation by convex lenses is illustrated by this example?

What is the effect on the size and position of the image of moving the object:

1. Towards the lens, and
2. Away from the lens?

On the basis of the possibilities of combination of the sex chromosomes, what percentage probability does a couple have of having a son or a daughter? Show the same by making a cross.

Calculate the work done in moving a charge of 4 coulombs from a point at 220 volts to another point at 230 volts.

Some of the important fossils which have been studied are those of organisms X, Y and Z. X were marine arthropods which were common between 400 to 600 million years ago. Y were the invertebrate animals (molluscs) with a flat, coiled, spiral shell which lived in the sea about 180 million years ago. Z are the extinct carnivorous or herbivorous reptiles which appeared on the earth about 250 million years ago and became extinct about 65 million years ago. What are X, Y and Z?

How much energy is consumed when a current of 5 amperes flows through the filament (or element) of a heater having resistance of 100 ohms for two hours? Express it in joules.

A concave mirror has a focal length of 4cm and an object 2cm tall is placed 9cm away from it. Find the nature, position and size of the image formed.