Life Processes — Science STD 10 — Question

Describe some of the problems associated with the construction of dams.

What will happen to the rate of photosynthesis in a plant under the following circumstances?

1. Cloudy day in morning but bright sunshine in the afternoon.
2. No rainfall in the area for a considerable time.
3. Gathering of dust on the leaves.

The electronic configurations of three elements A, B and C are as follows:
A 2, 8, 1
B 2, 8, 7
C 2, 4

1. Which of these elements is a metal?
2. Which of these elements are non-metals?
3. Which two elements will combine to form an ionic bond?
4. Which two elements will combine to form a covalent bond?
5. Which element will form an anion of valency 1?

List three main factors responsible for the speciation and briefly describe each one of them.

A dentist uses a mirror in front of a decayed tooth at a distance of 4cm from the tooth to get four times magnified image in the mirror. Use mirror formula to find the focal length and nature of the mirror used.

The optical prescription for a pair of spectacles is:
Right eye: 3.50D, Left eye: 4.00D

1. Are these lenses thinner at the middle or at the edges?
2. Which lens has a greater focal length?
3. Which is the weaker eye?

What is the maximum number of 60W bulbs that can be run from the mains supply of 220 volts if you do not want to overload a 5A fuse?

Mention the part of the brain involved in thinking. State one more function of this part.

The strategy of 3Rs' has become profound in environment management programme. Give reason.

At what distance should an object be placed from a convex lens of focal length 18cm to obtain an image at 24cm from it on the other side? What will be the magnification produced in this case?