Carbon and its Compounds — Science STD 10 — Question

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

State Mendel’s second law of inheritance.

What are the two negative impacts of a hydro power plant on the ecosystem?

The growing size of the human population is a cause of concern for all people. The rate of birth and death in a given population will determine its size. Reproduction is the process by which organisms increase their population. The process of sexual maturation for reproduction is gradual and takes place while general body growth is still going on. Some degree of sexual maturation does not necessarily mean that the mind or body is ready for sexual acts or for having and bringing up children. Various contraceptive devices are being used by human beings to control the size of population.

1. List two common signs of sexual maturation in boys and girls.
2. What is the result of reckless female foeticide?
3. Which contraceptive method changes the hormonal balance of the body?
4. Write two factors that determine the size of a population.

What are the various methods used for concentration of ore/Ore dressing?

State any three differences between the physical properties of metals and non-metals.

An electric kettle rated as 1200W at 220V and a toaster rated at 1000W at 220V are both connected in parallel to a source of 220V. If the fuse connected to the source blows when the current exceeds 9.0A, can both appliances be used at the same time? Illustrate your answer with calculations.

State the factors on which the strength of an electromagnet depends. How does it depend on these factors?

In what way can biodegradable substances be used by farmers?